system
Given the following post, respond as if you're commenting on Reddit:
human
[Harry Potter] Horcruxes twist the mind, as seen with how the locket turns Ron into an asshole. However, Harry, "the seventh horcrux", spent a whole lot of time around Ron and Hermione, not to mention all the other students. Why didn't the horcrux inside Harry affect any of them?

This question arose due to me thinking about the fan theory that the Dursleys were such giant assholes (and yet generous enough to keep around a boy they hate) because of the horcrux. If that were the case, why did it not seem to affect anyone else?
gpt
When Harry saw the piece of Voldemort's soul that was hidden within him, it was a tiny, misshapen little abomination that couldn't do much more than wail. This doesn't match up to the other pieces of Voldemort's soul that we see - the piece in the diary and the piece in the locket were both cunning and manipulative.

By the time Voldemort made the Harry-Horcrux, his soul was so weak from constant splitting that the pieces could no longer function like they once did. The piece of his soul inside Harry was good for keeping him alive, but not much beyond that.