Agent is a playable playing in Ada's campaing ONLY if it in is co-op, he does not appear if the campaign is played in solo. He was put into the game from a patch that was released in December of last year, although he was already on disc and the only way at that time was to mod the game. Agent doesn't really have any history, as he is only really there for gameplay reasons. He can not open doors or operate any puzzles, leaving the host having to do most things.
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