Although not played as such, Desmond is the main character of the Assassin's Creed series. Trained as an assassin, he uses the Animus to travel back into the lives of his assassin ancestors to discover secrets and abilities from their times.
From the original Assassin's Creed manual:
Blood Type: A+
Psychological traits: Independent, introverted and defensive. Desmond has trouble trusting others. His parents were incredibly overprotective, essentially imprisoning him within their community, swearing it was for his own good. He has spent the past nine years avoiding large cities, hiding from civilisation. He guards his thoughts and emotions behind a wall of cynicism.