"Blackwatch is just fuel for us. Healing, consuming, disguising. One way or another, you will get used to the taste of blood. Theirs or yours."

Trapped hiding in the relentless cold of the blizzard and the destroyed ruins of a forgotten Christmas celebration, you end up fatally injured in a fire fight between the government Blackwatch soldiers and Alex Mercer's Hunters.

Before you could bleed out on the street, he infects you and recruits you into his army, exerting his psychic and physical control over his newly created "Evolved" to force you to fight, hunt and kill. While Mercer is only occasionally satisfied by your growing abilities, his frustration grows at your moral resistance to becoming the bloodthirsty predator he's trying to train you to be.

(Based on the game, Prototype.)