In Harry Potter and the Goblet of Fire the Triwizard Cup was used as the portkey to send Harry and Cedric to the graveyard in Little Hangleton to face Voldemort.
Why was the Triwizard Cup chosen?
Couldn't Crouch Jr. have used anything as a portkey; which would have been much easier and without as much risk (after all of their planning Cedric almost ended up getting the cup first).
Harry is famous and well guarded. What better way of disposing of him while keeping Voldemort's return secret than by having him die mysteriously in a tournament with a history of killing its participants? Since they know he should be in the maze and they can't see him, his absence in the middle will never get noticed. No one else is ever going to touch the cup by accident (as would be much more likely happen if it was a sock, say), and Crouch Jr was using Imperio to get rid of the other contestants just in case; Cedric only reaches the cup because Harry saves him.
There are three critical components to consider.
One: There is the difficulty of using portkeys; portkeys are not supposed to be used unless prior authorization by the ministry has occurred.
Although it seems Dumbledore can easily break this rule;
"Now see here Dumbledore!" said Fudge, as Dumbledore walked over and picked up the golden head "you haven't got authorization for that portkey! You can't do things like that in front of the Minister of Magic!"
Order of the Phoenix Chapter 36 (pg. 818 in the Scholastic edition from 2003)
As far as we are aware, Dumbledore is the only wizard to break this rule and although he does so easily, there is another example in Order to prove breaking this rule is no easy task.
"How're we getting - wherever we're going?" Harry asked. "Brooms," said Lupin. "Only way. You're too young to Apparate, they'll be watching the Floo Network, and it's more than our life's worth to set up an unauthorized Portkey."
Order of the Phoenix, The Advance Guard, Pate 52 (Scholastic:2003)
In the example above, there were a number of highly capable wizards present, Lupin, Moody, Shacklebolt, . . . I'm going to say Crouch probably wasn't capable of it either, prior to training from Lord V and even then, it may have helped him in the measure of success he did obtain in that the trophy was already a portkey.
The Triwizard Cup was an "allowed" portkey that was authorized and was supposed to transport the winner out of the maze and back to the stands to be celebrated. Even if Crouch Jr. thought he had turned it into a portkey, in reality, he only altered it a little before placing it in the maze by adding an extra portus to the graveyard. Perhaps, this made Crouche Jr's job easier because there was no need for spells to make it difficult to detect an unauthorized key, perhaps it doesn't really matter in the end in terms of how difficult his job was and he learned what he needed from Lord V first, either way it was not, in fact, an unauthorized and brand-new made from scratch portkey, but already had the portus to the grandstands on it when Barty did his bit.
Two: Voldemort felt he needed to put on a show for his not-so-satisfactory-Death-Eaters (the ones not in Azkaban) to prove to them he was as powerful as ever.
While Crouch could have killed Harry and then escaped, Voldemort wanted to kill Harry himself and he needed Harry's blood. It hurt Voldemort's pride that he had been defeated by a baby and he felt he needed to prove there wasn't really anything special about, "the boy who lived." He talks about this need in "The Death Eaters" when he says:
"You know of course, they have called this boy my downfall. . . but no matter, I can touch him now! [Harry feels terrible pain in the next paragraph while V touches him]
he goes on, but you get the idea.
It is quite clear that Lord V understood he couldn't touch Harry because of what occurred in the chamber at the end of Sorcerer's Stone. Lord V needed Harry so he could have Harry's blood. Simply having Crouch kill him would not have worked because although it would get rid of V's need to touch the boy, it wouldn't get rid of his need to prove Harry was not his undoing or stronger than he.
Just before having Harry released for the Duel Voldemort says:
"You see, I think, how foolish it was to suppose that this boy could ever have been stronger than me, but I want there to be no mistake in anyone's mind. Harry Potter escaped by lucky chance and now I'm going to prove my power by killing him here and now. . ." Emphasis mine.
Three: Harry needed to be ported to Voldemort at an expected time and a particular place. I'm sure there was a complicated bit of spell work and a potion involved here. Who knows how long it took for the potion to be ready for adding Harry's blood in the first place. Keeping Harry captive for any length of time would likely have proved dangerous as it surely would have brought Dumbledore looking. One of the first things Dumbledore would likely have done once Harry had been identified as missing, would have been to check out any location connected to Voldemort and his past anyway.
Even though we don't know for sure they had to wait that long for the potion to be ready, We do know throughout the book, Voldemort is getting progressively stronger (Dark marks of Karkaroff and Snape as evidence). I'm sure he wanted to ensure sufficient strength for the spell to work and to look good for his cronies. So just having Harry show up whenever Crouch could happen to get him to touch the proper pen where no one else would see and at a time when he was not expected at another class or whatever would also have been risky.
Just for the sake of argument, let's say Voldemort felt he could keep Harry captive long enough for V's strength to be what it needed and the potion to be ready, how would he be sure to capture Harry if Harry arrived at an unexpected time? Until he was able to call the other deatheaters to him, Voldemort only had Pettigrew, Nagini and Crouch. Pettigrew was busy with caring for and strengthening V, and Crouch was busy with getting Harry to the set location. As we know, there wasn't anyone there to intercept Harry right away when he arrived in a short window of expectation. Had he arrived at the graveyard with a window of "any time that year" there would have been a chance he could have walked right out of the graveyard or some such other "escape." because no one was there to make sure he was captured. I don't think Voldemort trusted the other Deatheaters to let Pettigrew go through with it, he certainly didn't want all of them seeing him in his weakened state.
Finally, Voldemort intended that it would Appear as though Harry simply died/inexplicably went missing in the maze
It is mentioned in both the book and the movie that contestants have died battling in the Tournament in the past - this is partly why the age limit is added - to protect the younger witches and wizards that would be most likely to have the inability to protect themselves from a permanent injury or fatality.
Voldemort did not want anyone to know yet of his return, so he planned on using the history of occasional deaths during the tournament to his advantage. A death during any other part of the year would result in much stronger inquiry and much deeper searching into a cause. He hoped the tournament would provide a cover to explain Harry's death without too much questioning.
He still needed to be sure he was at his own full strength (including having all of his best supporters by his side - which meant breaking them out of Azkaban) He needed secrecy in order to easily free those Death Eaters still in Azkaban and to infiltrate the ministry sufficiently to prevent organized resistance on a government level.
Voldemort mentions to his returned DE's about gaining the allegiance of the dementors next and getting those "entombed in Azkaban" back and even goes on to mention getting the allegiance of the giants as well. While he doesn't explicitly identify an order of occurrences, within the context, it does not sound at all like a plan to reveal himself back at Hogwart's right away (650-651).
Additionally, Barty Crouch/Mad-eye Moody clearly expects Lord V to torture if not kill all of those who were able to go to the graveyard that night because they were neither locked up, nor dead. Certainly, he would not be under that impression if they planned to show up at Hogwart's ready for a fight after killing Harry (674-675).
The real kicker for me to refuting the idea that it was made into a return portkey by Voldemort/Crouch, is that Dumbledore points out,
"Voldemort has returned," Dumbledore repeated, "If you accept that fact straightaway, Fudge, and take the necessary measures, we may still be able to save the situation. The first and most essential step is to remove Azkaban from the control of the dementors" . . . Fudge reacts negatively . . . "The rest of us sleep less soundly in our beds, Cornelius, knowing that you have put Lord Voldemort's most dangerous supporters in the care of creatures who will join him the instant he asks them!" said Dumbledore. "They will not remain loyal to you, Fudge! Voldemort can offer them much more scope for their powers and their pleasures than you can! With the dementors behind him, and his old supporters returned to him, you will be hard pressed to stop him regaining the sort of power he had thirteen years ago!"
Emphasis is mine - pg 707.
The reason this is a key ingredient in this discussion is that it shows clearly, Lord V still had work to do before the likes of Dumbledore would consider him a truly serious threat - and that it was work that needed doing before the ministry knew of V's rebirth. Showing up at Hogwart's triumphantly having killed Harry was most definitely not V's plan here. He is pompous and proud enough, showman enough to want that, but also way too clever to do it and let his secret out way too soon for ultimate success. He still fears Dumbledore and doesn't ever seek out having to kill Dumbledore himself because of that fear.
For these reasons I am convinced the "return" aspect of the portkey is placed there by Dumbledore (or someone else he trusted such as Minerva) before he ever hands it over to Barty to take into the maze. It is placed there as a convenient way to get the winner of the tournament to the stands and out of the maze, as well as a sure-fire way to know who the winner was in case of a close race. Barty and Lord V would have considered such a prior portus irrelevant and of no concern because it simply, would never get used (in their thinking). Or, they may have even considered it advantageous as it made it easier to add the portus charm to the graveyard without discovery. They would never have considered the possibility of Harry's escape from Voldemort in the first place so they certainly would not have bothered with trying to remove it.
This leaves only one hole I can think of
How did Voldemort figure on explaining the disappearance of the trophy? My conjecture is that he didn't. Voldemort does have a history of overlooking plenty of details throughout the books. The love of mothers for their sons is only one of these details.
And I'm not just speaking about Lilly's love for Harry. Narcissa's love for Draco is included here. Then there is also hiding the diadem right at Hogwart's in a room he somehow supposes others won't find. Or what about Kreature's role with the locket and the idea of Regulus defying him? . . .
The list of overlooked details on the part of Voldemort could be quite long if I really got into it. The point is that it is completely feasible that Voldemort would overlook such a detail figuring the ministry might figure something had also happened to it when Harry also disappeared. Or, Rowling overlooked that detail herself or both.
Cedric got to the cup first because Harry helped him out of two tight jams.
Cedric took a deep breath. ‘You take it. You should win. 'That’s twice you’ve saved my neck in here.’
‘That’s not how it’s supposed to work,’
Goblet of Fire - Page 549 - British Edition
I think Crouch Jr. anticipated Cedric's fair nature and felt he wasn't much of a risk. I would guess that he used the Triwizard cup as the Portkey because he knew that Harry would have to touch it. As well, Voldemort was very weak physically throughout Goblet of Fire -- perhaps it was a timing issue -- Voldemort may not have been strong enough to withstand the regeneration potion until the time of the third task, and so the Triwizard cup made sense logistically as the Portkey to the graveyard. Crouch Jr. could have used any object, sure, but there would have been less of a guarantee that Harry would touch a random item just lying around.
Voldemort is obsessed with important artifacts; the whole point of Half-Blood Prince was to show that his horcruxes were all important objects with significant history. Knowing Voldemort's fixation on such objects, it's completely in character for him to want to use the world famous Triwizard Cup to bring his arch-nemesis to his demise, rather than some random, ordinary object.
I’m going to make some suggestions that might help us make more sense of, Why the Cup?!
Voldemort’s Power: While Wormtail suggested that they could use someone other than Harry and get the thing done with a lot quicker, it is rather evident that Baby-mort was gaining power throughout the course of the book. The Dark Mark tattoos kept getting clearer throughout, as we heard from both Karkarov and Snape. Frequent mentions were made about Dumbledore “reading the signs.” It seems a reasonable explanation that Voldemort wanted to wait long enough to achieve a certain amount of regained strength, even in his defeated form, before the re-birth occurred. We have no idea what kind of magic took place in that cauldron, but it might indeed be a process that could have failed had Babymort not been strong enough.
Voldemort’s Planning: Voldemort is very patient and cunning. As the symbol of pure evil in the series, it’s likely that we can draw some parallels between him and the current world threat of terrorism, which also embodies one of the clearest forms of present-day evil. And we know terrorists are patient and cunning. They are willing to wait as long as it takes to make sure their plans go correctly.
As such, it would also make sense for Harry to grasp a portkey at a time when it would not be noticed that he was missing. Were Harry expected in a class, at lunch, or back in the common room after an office meeting with Faux Moody, people would have noticed he was missing. At the Third Task, however, no one had any idea how long it would take the champions to find the cup. The whole plan moved him at significant distance from Dumbledore and the rest of the school, ironically, during the very time that they were most aware of Harry’s absence!
The idea was that Portkeys don't work inside Hogwarts, and Harry was not supposed to ever leave Hogwarts the entire year (though he did sneak out to drink some butterbeer), because the Dursleys never signed the permission slip. The cup was located off the Hogwarts campus, and planting Harry as a contender for the cup forced the Hogwarts staff to let Harry off grounds long enough to touch the portkey.
-1 to Rowling for contrived plot. Everyone reads it anyway.
I found an answer I like at an external location. Essentially the author of the essay ponders the same question that I do and asks why use the Triwizard Cup as the portkey. They bring up the point that the Cup was rigged to also be a portkey back to Hogwarts. But if the plan worked and Voldemort would have killed Harry then why rig the portkey to go back?
At this point Voldemort and his minions touch the Portkey and return to Hogwarts to begin the new Reign of Terror. This is why the Portkey was rigged to return to Hogwarts.
They arrive outside the maze, with Harry's lifeless body (after all a good gloat is needed) and begin decimating the future wizarding population. They're merely students (and not just Hogwarts students either, but Beauxbatons and Durmstrang as well), easy prey. Also in the arena is Karkaroff the coward, Snape the spy, Bagman, Minister of Magic Cornelius Fudge, Dumbledore, and, of course, Crouch as Moody. Crouch didn't just "forget" to take his Polyjuice Potion. It wasn't needed. He could begin hurling hexes as Moody (in all the chaos who could tell for which side he was playing?) and after the potion wore off, he could fight clearly as himself, alongside his Dark Lord.
After the battle, Voldemort would be in absolute power and all would be right in his world.
It was so brilliant. It was so simple. It should have worked.
I don't think the answer is perfect but I do think it offers up a plausible solution and covers most of the bases that I've had problems with.
Voldemort and Barty Jr. hatched the plan that unfolds in Book 4 to get Harry away from Dumbledore in as discrete a manner as possible. While any Portkey would have done the trick (whether inside or outside Hogwarts castle or the grounds), it would be very difficult to ensure that Harry would be the one to trigger it, while at the same time not making it perfectly obvious that Harry had disappeared, thus provoking Dumbledore's wrath. At the time, Harry was lost in the maze, and only Mad-Eye's eye could see through the hedges, so only he and Harry knew exactly where he was at any given time. Had Voldemort's plan gone off exactly as expected (with Harry dying in that graveyard), Dumbledore wouldn't become suspicious until hours later when it became obvious Harry was no longer in the maze at all, and it would take hours or days more to figure out exactly what happened and by then Voldemort would be dozens of steps ahead of Dumbledore and the Order.
Even given all this, if Cedric hadn't shown his nobler side (in the book) and walked away from the Cup to give Harry the opportunity of suggesting they take it together, it would all have been for nothing. Cedric would have disappeared along with the Cup, Voldemort's plan would have failed, and we wouldn't have known anything about it.
First, the Triwizard Cup was already supposed to be set up as a Portkey, to take the victor out of the maze. It would have been easy for Barty Crouch Jr. to add an extra stop to that, as the cup was already an authorized Portkey. Second, Voldemort couldn't just return unseen, killing Harry in the process, in the middle of the Triwizard Arena. So, he would return in the middle of a graveyard, no one would be the wiser, and Harry would be dead. Simple. Third, has anyone else noticed that Voldy tends to have a flair for the dramatic? He would kill Harry in front of all the Death Eaters, proving that after death he was just as evil, and scaring all of the cowards, like Pettigrew.
Harry would also be weak and tired, meaning Voldemort should easily defeat him.
I think its because Voldemort wanted a long time to be with harry for his Resurrection, and they needed time to set up for his resurrection. I believe he intended to use the portkey to come back to Hogwarts disguised as Harry (using a polyjuice potion), and kill Dumbledore when he wasn't expecting it. My evidence: First: I want you to think. Think about all of the portkeys ever used in Harry Potter. The only one that was two-way (it will take you back to where you left from as well as where you are going) was the Triwizard cup, which supports the part of my theory about Voldemort getting into Hogwarts. Next: Why would Voldemort, newly resurrected after 15 years of being "less than the meanest ghost", risk fighting Harry in a duel, and give him back his wand for it. He doesn't have to prove that he is better than Harry, since the Death Eaters fear him and wont think anything of it if he doesn't battle Harry (well, out loud and with actions, at least), so he could have kept Harry tied to the tombstone and killed him, witch would have the same outcome as the duel (what Voldemort wanted to happen). Instead, he lets Harry down and gives him his wand so that they can duel. I believe he did this so that he could win Harry's wand, so that when he went over to Hogwarts, he would have the full, working disguise. Voldemort never really understood wand lore, so he might have heard that a wand will work for you if you win it from its owner, but being Voldemort, he probably thought that that meant he has to battle the person, and kill them to win. That isn't the only reason why he would wait till the end of the year, and use the triwizard cup as the portkey. If Harry suddenly went missing, Dumbledore would be able to guess it was Voldemort who caused it, and deduce that Moody is an impostor, all of which, as Hermione states, is the last thing Voldemort would want once he was resurrected.
The potion to resurrect Voldemort wasn't ready until the end of the year.
What would Harry do in the graveyard until then? Just sit down, twiddling his thumbs?
Also, if Harry took a Portkey to the graveyard too early, Dumbledore would have to search for a missing student.
We can see very clearly that the Triwizard cup was made into a Portkey for a quick escape from the finality of the gauntlet when the hedges began to close shut and would've crushed Harry and Cedric with no other way out besides a Portkey. Someone changed the location of the Portkey (probably Pettigrew) to bring Harry directly to Voldemort.
