After Regulus Black was killed in the cave by the Inferi, did he join them and become one or just die? It seems transforming potential rivals into your own defence would have been wise, but do we know it happened?
2 Answers
The books don't say.
However, we do know that Regulus ended up in the water:
And he drank - all the potion - and Kreacher swapped the lockets - and watched ... as Master Regulus ... was dragged beneath the water ... and ...'
Harry Potter and the Deathly Hallows - p.162 - Bloomsbury - Chapter 10, Kreacher's Tale
And Harry deduces that the point is, indeed, that ending up in the water would turn you into a defender of the Horcrux:
... and his feet left the ground as they lifted him and began to carry him, slowly and surely, back to the water, and he knew there would be no release, that he would be drowned, and become one more dead guardian of a fragment of Voldemort's shattered soul ...
Harry Potter and the Half-Blood Prince - p.538 - Bloomsbury - Chapter 26, The Cave
On the whole, I agree that it's the only thing that makes sense. The potion causes an unquenchable, irresistible thirst. The water is the only thing that will work and all who enter the water, remain in the water. And those who are in the water seem to defend the Horcrux, so I agree that yours and Harry's surmise makes a lot of sense.
It is true that there's no explicit evidence of Inferius-ification, if you see what I mean? However, that water is more than water:
Harry looked back at the water. The surface of the lake was once more shining black glass: the ripples had vanished unnaturally fast; Harry's heart, however, was still pounding.
Harry Potter and the Half-Blood Prince - p.525 - Bloomsbury - Chapter 26, The Cave
We also do not know the full effects of that potion.
On the whole, I would not put it past a wizard like Voldemort to have those who end up in his lake become guardians of his soul fragment. Far from it, in fact. The entire set up seems to make little sense without that speculative component.
I also think it's very noteworthy that Voldemort makes Kreacher drink the potion and then drops the Horcrux into the basin, refills the basin, and sails away, leaving Kreacher there. His experiment is apparently complete. He sails away and leaves Kreacher to his fate, without - apparently - performing any further spells on him. Kreacher then, of course, succumbs and attempts to drink the water and gets pulled in. Job done, thinks the Dark Lord. That, apparently, is enough for him.
If more is necessary to make Kreacher a guardian, why not wait for him to die and do the magic? Well, maybe Voldemort never much fancied a House-Elf guardian and always intended him - and any other entrants to that cave - to lie silently at the bottom of the lake, with only the original Inferi as guardians. Maybe. But it all seems convoluted and pointless, if so. If so, why not just fill the basin with slow-acting poison? For sure, Dumbledore suggests that the Inferi and the darkness are there for the fear factor, as much as anything else. And it certainly seems that Voldemort wanted a potion defence that one could drink, allowing him to retrieve the Horcrux if necessary, but that would be disabling. But without the - oh and it makes you a guardian too - component, where's it really going? Why not just have it kill you outright? Why have it make you join the legions of the dead in the water?
However, the strict answer to your question is no, we do not know.
'A five-year-old could have told us as much,' sneered Snape. 'The Inferius is a corpse that has been reanimated by a Dark wizard's spells. It is not alive, it is merely used like a puppet to do the wizard's bidding. (HBP, Chapter 21, "The Unknowable Room")
This seems to imply that Inferius is created by a conscious effort of the wizard (casting a spell).
And we know that Voldemort most assuredly was NOT aware of Regulus's visit to the cave, as he didn't know that the Horcrux went missing till he visited the cave again in Deathly Hallows.
Harry closed his eyes, and as his scar throbbed he chose to sink again into Voldemort’s mind... He was moving along the tunnel into the first cave... He had chosen to make sure of the locket before coming…but that would not take him long... (DH, Chapter 30, "The Sacking of Severus Snape")
...
As she said it, a wrath that was like physical pain blazed through Harry, setting his scar on fire, and for a second he looked down upon a basin whose potion had turned clear, and saw that no golden locket lay safe beneath the surface -.
So there was nobody to turn Regulus into Inferius.
So the answer is "NO"
Having said that, purely theoretically, wizards can leave spells that hang on a trigger (e.g., cursed objects start the curse on anyone who touches them; or alarm spell triggered by Harry in front of Aberforth's pub in DH; or for that matter Taboo spell created by Voldemort); so presumably there's an off chance that Voldemort left a "Turn any intruder into Inferius" spell in the cave which triggers if anyone is killed there. However, there's precisely zero support in canon that such a thing has happened, so I'll reject that theory as extremely unlikely.
answered Jan 10, 2016 at 22:08
