emma/loki.
They haven't, but that isn't to say they couldn't. Or that they couldn't level this whole mountain because they woke up on the wrong side of the bed one day. Or, perhaps, whatever caused your magic to ricochet finds them next.
Some may insist prevention lies in control. I say, why not figure out what made things go wrong and prevent it from happening again? Obviously despite that several of us are entirely capable of widespread annihilation, we don't explore that. (I pride myself on such character growth.)
Besides, I know what it is to have something dark inside. I spent centuries on fire, burning alive and unable to break the cycle.