I’m not capable of reasoning about time loops in my sleep-deprived state, but would it be possible for Hermione to create her Horcrux by killing herself?
Yes: Consider the following loop: Hermione A goes and kills future Hermione B (who already has a horcrux). Hermione A is then killed by the troll, but has a horcrux (possibly with a mind wipe before so she doesn’t know about it). Hermione is then A is then resurrected to be sent back in time to become Hermione B. Then Hermione B is resurrected.
However, we know that messing with time is bad and we know that magic with souls is powerful, so this combination looks potentially very dangerous.
More generally, if resurrection doesn’t require additional sacrifices and doesn’t use up a horcrux, people who don’t have horcruxes could make them by murdering other people (by arrangement) who already have one (and then resurrecting them). Eventually, everyone is alive and has a horcrux.
I’m not completely sure this will work in general. It seems that magic works partially off of intent. One may need to actually believe that one is murdering the person in a permanent way. However, even that could be handled with memory charms.
I’m not capable of reasoning about time loops in my sleep-deprived state, but would it be possible for Hermione to create her Horcrux by killing herself?
Yes: Consider the following loop: Hermione A goes and kills future Hermione B (who already has a horcrux). Hermione A is then killed by the troll, but has a horcrux (possibly with a mind wipe before so she doesn’t know about it). Hermione is then A is then resurrected to be sent back in time to become Hermione B. Then Hermione B is resurrected.
However, we know that messing with time is bad and we know that magic with souls is powerful, so this combination looks potentially very dangerous.
More generally, if resurrection doesn’t require additional sacrifices and doesn’t use up a horcrux, people who don’t have horcruxes could make them by murdering other people (by arrangement) who already have one (and then resurrecting them). Eventually, everyone is alive and has a horcrux.
I’m not completely sure this will work in general. It seems that magic works partially off of intent. One may need to actually believe that one is murdering the person in a permanent way. However, even that could be handled with memory charms.