Hi Leila! I'm Joey (Joe-ie), and I play only one character: Dedalus "Digs" Diggle.
Much like Mac, Digs is incredibly impulsive, balanced by a need to know everything about...everything. Digs is the most loyal, friendly, and absolutely nuttiest person you will ever meet. And because Mac and Digs have so much in common, I see no reason why they wouldn't get on perfectly. Digs could use someone to get in trouble with.
In recent episodes, Digs has found himself getting shot at for obtaining an item of some sort (that hasn't been revealed yet), and otherwise causing trouble for everyone on the road trip by driving a big, obnoxious lorry.