I saw a player that had a purple name. Does anyone know why he has a purple name?

Brink has a lightly explained Fireteam system. He was in your fireteam. This means he could listen to your conversation [if you or him had a head-set]. I usually play with a friend in an xbox party, which means I see his name in purple to highlight he is who he is, which makes it easier for us to stay close since we can hear each other talk. I've noticed sometimes an AI bot will somehow become part of our fireteam. I'm not sure how the game determines this other than party-mode. I do know you can invite people to your fireteam by going to the scoreboard, selecting their name, and thusly inviting them.

I believe that means he is part of your fireteam.

Edit: Dang, Necrotic is a fast typer.

...? I need to look into that. I shouldn't be apart of a fireteam.

Also, when you stay in the "lobby" after a match and load a new map everybody on your team will likely be different people, except your fireteam. They will stay with you until you go to the main menu, I think.

If he has a purple name then he is on your friend list.

If he's on your friend list he'll automatically be in your fireteam when you're both in the same game - purple means fireteam, not just friends.

It also applies if they're not in your friend list but they're in your party.

Ummmm...

Party = fireteam...

See, this is the weird thing. He is not on my friend list, I was not in an party.