Hrm. Most of the folks from Kol's old life would likely be hostile (though an instructor or priestwho understands his reasoning is a possibility). As part of the bonus from the Trait: Drug Addict (Friend) is a +2 to Knowledge: Local, I'm going to assume he's been out in the city a few weeks now.
How about:
His first night outside the temple, Kol was wandering through the city with little in the way of a plan to find Lamm. He came upon a shopkeeper being assaulted in a back alley, and immediately found an outlet for his frustation and guilt, beating the mugger bloody, then escorting the shopkeeper home. He now lives above his/her shop, doing odd jobs for rent as he learns the ins and outs of the city.
I can add on as many details as you'd like, but have left it intentionally vague at this point to give maximum flexibility.