Why did Smeagol turn into a 'creature', but not Bilbo Baggins?
Deagol found the ring in a lake, Smeagol stole it and then turned into a weird creature. Bilbo did not turn into a creature when he found the ring.
Bilbo DID become addicted to the Ring - when it came time to part with it, he had a full on freakout:
And there we go. "My precious".
... and yet, he STILL doesn't part with it:
And later on, Gandalf confirms it to Frodo:
The only 3 thing that differentiated them was that first, Bilbo owned the Ring for a far less time than Gollum; second, that he didn't use it extensively; and third, that he was clearly a better, more "pure" person than Sméagol, who, if we recall, murdered his best friend the moment they found the ring.
Not only that, but we see that the Ring even became addictive to Frodo, from the first moment he dealt with it, when Gandalf advised him to try to hammer it to destroy it:
and later, when Bilbo tried to get to see the ring in Elrond's palace:
As @Mchl correctly noted, there are also examples of Frodo becoming addicted, and he was associated with the Ring less than Bilbo clock-time-wise. I omitted them from the answer since the question was about Bilbo.
Bilbo wore the ring for substantially less time than Smeagol/Gollum (who was estimated to have been a ring bearer for nearly 600 years) but even limited exposure to its presence caused his behaviour to become erratic. He was incredibly reluctant to part with the ring, periodically wore it (despite dire warnings from Gandalf) and on one occasion, he flew into a rage at the suggestion that he give it up. All of these are classic symptoms of an addiction.
In terms of the physical changes, we can see from the film that those were starting to occur too;
Remember Tom Bombadil - who does not appear in the films; which takes away an important foil to Sauron. He is not affected by the ring - Frodo puts it on and he can still see him - it bears no power over him. The ring affects the weak more - the weak of character, the weak of will, the people who do not have anything to live for; who have nothing which would dissuade them from succumbing.
It can be seen as like heroin - I always have done, I don't know if this is a common parallel that is drawn. (Tolkien meant the book to be a reaction to the rise of Nazism). If you see some junkies on the street, who look awful - they look like Gollum and they would do anything to get money for the drug - I am not saying they would kill their best friend as Gollum did, but you hear stories. It consumes them and destroys their lives.
Some people try it, or do it occasionally, it does not take over their lives - they would not do 'anything' to get it... Why? Perhaps they have more to live for. They have a stronger character. A drugs takes as much from you as you let it. When it does take people over, it usually does coincide with a loss in their lives - making them weaker.
To sum up, some people are stronger than others and have more to live for. Bilbo is a strong character, as is Frodo: they are led by their morals and a sense that they are working towards a greater good: it is this perception and understanding of a greater good that makes Frodo risk his life; that makes Gandalf sacrifice himself. This, rather than giving them a burden; something they must to; protects them; it rises them above where they would be otherwise and gives them something to live for.
Likewise; if you want to rehabilitate drug-addicts; don't fight the physical addition in isolation: fight the social addition, which is far more pernicious: if people have nothing to be clean for, they will not be able to be. The best help you can give anyone is to give them something to fight for: something that makes them feel they are part of something which is bigger than themselves, and that with others as a group, they can achieve what they could not on their own. Bilbo and Frodo are saved from being consumed by the ring because they have a much more powerful drug; they are able to fight to rid the world of an evil that has the power to harm those they care about.
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Beside the time period...
Smeagol started his bearership with a profound act of evil... the murder of his friend and I think due to that he was much more susceptible to its influence. Bilbo began his by chance, and an act of mercy sparing the creature Smeagol had become.
Pure speculation here, but behind the scenes, so to speak, Sauron had slowly been regaining power, so perhaps there was less outside influence on Bilbo (during the pre- LOTR time) than on Frodo.
I'm tempted to suggest that, in addition to the time difference, Smeagol was living alone, isolated not only from his family but even from vaguely related species, while Bilbo had the emotional support of his entire village :-).
The other answers explain pretty well how Bilbo was affected by the Ring as well.
As for why Gollum was ... well ... Gollum (and Bilbo wasn't):
Bilbo used it much less than Gollum. Gollum used it to catch food and hide from orcs, so he would be wearing it quite often. Bilbo would not need to wear it, he was an upstanding member of society who probably could feed himself well. (On the other hand, Smeagol had been banished by the other hobbits, and had to fend for himself)
Additionally, Gollum is very old, it may be possible that he wasn't in such a bad state while a hundred years old.
I would suggest that "addicted" is the wrong terminology here. "Possessed by" or "obsessed with" the Ring would be a better description of what happened. (In the book, I believe it is described as the ring having a "hold" on the character.)
The Ring in LOTR is frequently described as an entity all of its own. It speaks of the Ring seeking to return itself to Sauron, and that it is using the various ring bearers to do so.
Gollum held the ring for significantly longer than Bilbo, and therefore its hold on him was more considerable. It warped his personality from Smeagol to that of Gollum. He was possessed by such a desire to keep it secret that he hid himself in the cave and became the creature Gollum.
Bilbo, in the years he possessed the ring, did not seem to wear it particularly often. (At least this is implied in the books.) And, notably, even when it was time to give up the ring, it seemed to work its way back to his hand or pocket numerous times. (See above)
In fact, the final time he puts the ring on, it is described as practically leaping onto his finger.
Thus the ring seems to have a mind of its own, and would be more of a possession than an addiction.
I would say that there are many valid points given, but one truly missing item is Light. In particular, Gollum hid from the Light in all forms. When daylight became too strong after possessing the ring, he sulked around only at night. When the light of the stars became too strong, he then hid from all Light under the mountain. The stars were put into the sky by Varda (Elbereth) "In light is her power and joy" and she is even more feared by Melkor than Manwe, according to The Silmarillion. Light is then feared more so by Dark than anything else.
A hobbit, on the other hand, truly enjoys Light, in some ways even more so than the Elves or any other creature. You could say that they have a Lightness to their internal morality. Gollum had an internal darkness due to his actions (murder/theft/betrayal/lying.)
It's the basic core struggle between Light and Dark, Good and Evil.
A hobbit is not immune to Evil, as over time Bilbo's behavior had changed somewhat, at least in regards to the possessiveness/selfishness of the ring. He had possession of the ring for decades, whereas Gollum had it for hundreds of years. It's not guaranteed that Bilbo would have turned into another Gollum if he possessed the ring after 600 years - I would assert that he would take much, much longer to get to the broken down physical/mental state of Gollum.
Frodo had the ring in his every-day-control for about a year and he became obsessive. I believe this was accelerated due to the exposure to the ring wraiths and the proximity of Sauron. As he physically came closer to Darkness/Evil, and even infected by it by the stab wound, he became more obsessive of the ring than even Bilbo did. (Bilbo voluntarily walked away from it after all.)
For a short time, and in a remarkably quick fashion, Gollum started become free of the Darkness from the ring while he was being treated fairly by Frodo/Sam and as he helped them in their sacred quest. (He was exposed to Light-based behavior and reciprocated in kind.) This just goes to show that a little Light covers a lot of Dark! He wasn't even cursing the Sun when he temporarily became friendly. Given enough time exposed to Light, Gollum may have eventually been a permanent convert.
It would follow that anyone anyone exposed to the Dark is negatively affected by it, and anyone exposed to the Light is positively affected by it (to a greater degree than Darkness.) The amount of the affect is determined by comparing the current internal state of the person involved, the amount of the Lightness or Darkness involved, and the willingness/desire of the person to accept the gift/curse.
A side - the ring didn't initially work on Tom Bombadil. He was so full of Light that the Darkness had no affect. In my opinion, he was a hobbit version of a Maiar. Even Tom would be corruptible given enough effort by Darkness. (He could possibly be immune to Sauron, but not Melkor.)
We could further discuss Galadriel's temptation, but to cut this short, given the formula above, the higher the status in a society the more easily tempted for Darkness due to the individual's desire for power. To relate to today's events - we would all be likely better served by plucking an individual off the street at random to become president than spending a billion dollars on a single campaign. The higher the stature, the greater the corruption. In JRR Tolken's experience, nothing likely exhibited it more than Adolph Hitler and Joseph Stalin who both killed millions. Ultimate power leads to extreme corruption.
Note - my first answer here...I stumbled across this interesting question while viewing Stack Overflow and decided to compose what I have typically inferred in regards to this topic.
Smeagol withdrew from society and spent around 600 years in a cave with only the Ring for company -- far longer than his normal lifespan. As a result, his body changed: He skin became pale, his body gaunt, and his eyes became bigger to help him see better in the dark.
After all that time in a cave, alone, living off of scraps, he became even more eccentric; and couldn't stand sunlight or "normal" food. Gollum was the product of spending so much time in the presence of something dark and corrupting.
Bilbo, on the other hand, still lived in the Shire (he didn't need to run away, like Smeagol did) and only spent 60 years with in the company of the Ring. Despite this, the Ring was growing in power while he held it, and even though it didn't have time to corrupt his body and mind as completely as Smeagol's, it did take its toll on him.
Because it's the ring that controls the character. Whoever had it for long would tend to fall in love with the ring and do everything in their power to not lose it. Since Bilbo only had it for a short time, shorter than that of Gollum, that's why he is not that much in love with the ring. If you watch the movie carefully, Bilbo does fall in love with the ring as time goes on. And he has a hard time giving it up at the end.
One thing that people seem to be missing here is the condition of the ring bearer. Many of the above are true and right!
But consider these points:
1) as Gollum wormed his way under the mountains, he grew gaunt and pale - obviously his body was missing things to get healthy - there fore the Ring supplied some things to him. This changed him utterly. He lost the ring in the year Third Age 2941.
2) Bilbo, not only having the ring 1/10 the time did not (as stated above) use the ring as often. But more telling IMHO is that he was well fed, comfortable, and most importantly, Sauron was not yet searching for the ring. It is only when Gollum leaves the mountains and is caught does Sauron learn the One Ring had been found. As Sauron gained power he searched for the ring, it began trying to get back to him - thus Bilbo telling Gandalf "it has been growing on my mind lately".
3) Frodo had received the ring in TA 3001, and he was well fed and comfortable. The hobbits left the Shire in TA 3018. He only had large lapses of control of himself when in relative close proximity to the Dark Lord's power; i.e in the Shire, on Weathertop, etc. As Frodo was wounded on Weathertop and then began to get closer and closer to Mordor, the ring's power grew and its hold on Frodo did too. This was especially evident as they grew hungrier and had less energy: Frodo's will power was taken up more and more in resisting the ring. Finally being half-starved, in Mt. Doom in the middle of Mordor he succumbed. Gandalf gave him credit that he resisted the ring better than most. You can see how it affected both Boromir and Denethor and neither ever touched it. Galadriel herself was tempted when the company was in Lothlorien.
First off, I didn't read all the comments, so sorry about that. But if I remember correctly Smeagol is part of the 'River Folk' who aren't necessarily Hobbits.
That could explain the difference.. and of course the fact that he killed to obtain the ring and spent many years with it in exile (and the dark).
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