Speculation ahoy

I'm pretty sure the red-haired ml boy only destroyed mc's family within the novel bc of that mana mind control thingie, so she's doing more preventative work.
It doesn't make sense for the guy to have been okay with killing the people he grew up along with, even if they weren't besties, and mc did mention that he had kind hidden side too.

I also really really really really really hope that the og fl and our mc will team up instead of going against one another. Imagine they are upfront about the respective regressor/reincarnation situations and vent to each other about being tiny humans again, and plotting against the real bad guys in their chubby lil baby bods.