I'm looking for a single word that describes the younger man in this relationship:
A cop in his thirties befriends a seventeen-year-old kid he picked up on the street. He sees a younger version of himself in the boy, and the boy doesn't have a father figure in his life (he's being raised by a single mother), so the cop takes him under his wing. They develop a very tight friendship and have a relationship somewhere between father-son and siblings, though probably closer to the older-younger brother relationship.
I need something stronger than "friends," but since they're not actually brothers, I can't use that either. Similar to "protege," but with a less official connotation (and he's not training the younger one to become a cop).
Best Answer
I think you can describe the relationship as brotherly or fraternal suggesting that they are like brothers:
Given the context described and the fraternal relationship, the younger man could be referred to as the policeman's little brother: