if you give a fairy your heart, it will resent you. yes, maybe it threatened to steal it, but in that case you should have just let it. fairies love to steal, but you took out all the fun by preemptively giving it, and not trying to get it back. now it’s got this thing to take care of, to water? feed? how do you take care of a heart anyway?
maybe it will try to make a game of it. maybe it takes good care of your heart for a few months and is charmed by its beauty as it thrives, and thinks, ‘maybe there is something to this game!’ maybe then it gets distracted and when it remembers to check in on it it’s wilting. putting on a brave front and pretending everything is fine but the fairy can see it’s sick. because the fairy neglected it.
maybe it weighs on it like a heavy burden. and fairies are too small for burdens. they are too small for the consequences of their actions. they are too small for guilt. how did it get into this mess? it doesn’t remember ever wanting this. it must have been tricked! but it looks at you, pathetic, mortal, made of earth, and remembers you’re not capable of such glamour. so it shrugs, and flies away.