Here's a good question. How much would they know about each other? I was thinking their teammates could say a few things about their opponents and that would introduce them to each other indirectly. Something along the lines of "See the new guy? They say he's just some punk off the street they brought in to replace the usual guy..." or something to that effect.
Also: How much do you want to know about Kaz in OOC? I have a pretty good idea so far. Absent father, honest hard working mother, no siblings, works when he can, steals when he can't.