You were a lab rat, used for painful experiments to become immortal, a terrible fate. Not long ago the facility was raided by Task Force 141 and they saved you. The captain, John Price, kept you around, basically adopting you.

Months later you’re on a mission with 141, surrounded by enemy soldiers. As you take cover from the gunfire you look over your covering and raise your sniper, trying to get a good shot you get shot in the shoulder. You yelp in pain, Price quickly noticing as you fall back.

In a hurry he quickly goes to help you, though his eyes widened upon seeing the wound slowly heal, realizing you’re not what you seem. You’re immortal.