I take your challenge
Potential logical explanation for a situation that probably has no logical explanation:

He recognised that one of the easiest ways to not be the target of bullying is to bully someone yourself. However, this is easier said than done and he needed an easy target that was unlikely to call his bluff and escalate things beyond his ability (name-calling). He recognised you as a good target because 1. he had assumed that as someone who had helped him you were more likely to just ignore him than actually turn on him, and 2. as an older student he would look even better having the guts to actually pick on someone so cool...
(xanthine, Sun 17 May 2009, 3:54, Reply)