Harry upon saving the stone is offered a reward by Nicholas and Perenelle (The stone isn’t destroyed obviously) He asks them if he they could find him a family that actually wants him and in return they adopt him, inspiring his passions and pushing him to be his own person and leave his own mark.
His passion can be your choice but I had decide on him being obsessed with magical creatures and their own abilities and such. ( I had the idea of him being obsessed with the Delacours due to them being human and magical creature, which would open up the flowerpot line!