Hi /adv/
I went to high school with this guy, and now he's in the same university as me. He's started talking to me at random, every day, acting as though we are good friends and making small talk.
He's a nice kid and I don't have anything against him, but he gives me a bad feeling, and frankly, I don't want to be friends. What do I do? I don't want to offend him or make him think there's something wrong with him, but he isn't getting my hints that I don't want to keep talking.
Clear direct communication that you're not interested and terminate the 'friendship' and don't look back.
It's better to hurt someone upfront and let everyone know where they stand then nurse some awkward thing until it spirals out of control.
Write a decent letter, spell it out for him without being rude. Exit with closure. Leave no ambiguity, leave no hope.
As a dude that's how I would prefer it, no awkward maneuvering or guessing.