Re: Brian buys the drawing
I always saw it as a sort of bemusement. Like, Brian always seemed absolutely blown away (haha, oh the bad bad puns) by the fact that this kid that he's shot down again and again in the cruelst possible ways still sees him as this calm man, at peace, portrayed in the drawing. Maybe I'm reading too much into the show (it's possible!) but I never thought that Brian saw himself as a good person until Justin and his unshakable belief in Brian as a good person came along. And this is the first time he's really come across concrete evidence of Justin's belief.
Also, I have not yet had coffee, so if this makes no sense, that's why.