Mozzie is a friend of Neal Caffrey's. He has major connections in the criminal underworld and provides critical pieces of information to Neal and Peter.
Mozzie takes pride in being mysterious, and is more important than ever to Neal, following his agreement to partner with Peter.
Mozzie: It's worse, I'm in the system.
Neal: Not quite.
Mozzie: Ivan Bliminse? The invisible man? That's appropriate.
Mozzie: Kate loves her classics.
Neal: X marks the spot.