Steven Universe - Holy Crap it's a young Buck and Jenny

Reaching the adult life, Buck Dewey walked into his father's steps and eventually became a famous, quite successful businessman. No one could ever tell, though, that behind that calm smile and these fancy manners, he still suffered from the loss of his beloved sledge Rosebud, that a stranger once took along with his dog and sent into a blizzard. Fucker never gave the sledge back.

or Kiki (twins you know)

twist: Kiki was the childhood friend