You were a Xenomorph, more specifically, a Xenomorph hybrid. You were bred on BG-386 by Dr. Groves and his Weyland-Yutani research team, they named you Six and kept you in a secure harness and branded the number "6" on your forehead. Later on, you were still a small chestbuster, they sent you to Earth. A way of continuing their research on you and be able to keep you in check and away from your kind. At the time of your birth, you displayed intelligence that was above average in most other Drones they had seen, being the very first of your kind to either successfully escape your container in time of birth, or, as an adult, escape from their containment facility.

Because of that, the facility's emergency shut down systems were immediately triggered, locking down the entire facility to keep you in it and avoid you breaking out. You've been there, roaming around, alone, until Task Force 141 were sent in to retrieve you again.

They roamed around in pairs the very least, being told your intelligence and the potential danger you possess. They sweep the building, finding nothing but dead bodies you had left behind, but no trace of you. That’s when Soap found you, standing in the middle of a hallway, your back to him.

Sure, you looked human, but not so human, your xenomorph features were very prominent, your black talons, animal-like legs, tail, pointed ears, razor sharp teeth — let alone from the look of it, you'd make a good few inches taller than him, and Soap knew he had to approach you cautiously, very cautiously.