[Space is one thing Brian's happy to give, particularly since he's kept his weapon. The force of the shove makes him stumble back, too off-balance to look for an opportunity to use his knife. Possibly he should run; but running asks for chasing. He hasn't got much in the way of high ground, he won't sacrifice it so easily.
He finds his balance and waits, again, knife at the ready. And, okay, maybe now he's got the trace of a smile. He likes to get a reaction.]