Why is my cat obsessed with licking my other cats paws?

My cat, Pancake, about 3 months old, is obsessed with licking my other cats paws, Jasper, about 5-6 months old. She gets really into it, like they are the most deliious things in the world, she purrs really loudly when she does it too. When I pick her up and mover he away from Jasper she runs back and continues to lick Jaspers paws. Why is this?