Maddog is a native of Arulco and was very happy wrecking stuff with a crowbar until he was recruited into the militia during an A.I.M. operation. When the team left, he hid in their plane and just hung around the A.I.M. HQ. Even after A.I.M. was destroyed, he stayed near the wrecked facilities. He was never officially a member, but try telling him that...
"Stick it in your ass!"
"Father kill a human!"
"How can people question my love for this?"
"Next time I kill someone, I'll take their lungs."