League Buddy
If ONE League Champion was to come into your life by someway (imagination activate) and you then had to teach them how to fit in to your society and not destroy anything that pisses them off, who would it be. Limited to the Human Champions so no animals or Yordles, but i will make the acception of Zac if you can post a picture of him in a nice suit.
I would go with 
cause I really like her as a champion and trying to get her to act normal would be fun, first step would be to make her stop floating.
It would be a long time to teach him NOT to stab people and actually smile for once in his life. I'd try to make him get rid of his blades and leave them at home, but I'm afraid he'd resist...
Because I feel like he would be super famous once he learned that killing people and stuff is NOT okay, and I would be his less-famous companion of awesome.