Paladin Danse is a member of Brotherhood of Steel and is a reliable combatant. You can get him as a companion after completing the BoS sidequest Shadow of Steel. As you progress through the Brotherhood storyline, he'll be later revealed as a runaway synth during the quest Blind Betrayal. He may die or be spared, depending on the character's choices. If spared, Danse will become a permanent enemy of the Brotherhood and will be fired upon on sight. If set as your follower, you'll also become an enemy of the BoS albeit temporary until you dismiss him.
Extra skill/ability
Approval
Disapproval
Max Affinity Perk