Python

Python was a war buddy of Big Boss during the Vietnam era who was originally a member of FOX. Python's unique FOX sneaking suit color was light blue.

Background
Python and Big Boss fought in Vietnam together, and after The Boss died, Python was considered by Big Boss to be the one person he could count on in battle. However sometime during a secret mission in Vietnam, Python received a severe injury which cost him the ability to regulate his body temperature, and as a result, Big Boss presumed him to be dead. Without intense medical care, Python would overheat to the point where his body would literally burn itself up.

His body was recovered by the United States government and eventually put through surgery in which he was fitted with a specially designed cooling suit filled with liquid nitrogen, complete with metal shunts installed in his skull to relieve himself of excess heat. Because of this, he was able to freeze objects that are close to him by flushing the liquid nitrogen inside of his suit out into the environment, though by doing so he would lose some of the cooling agent, making him heat up slightly. He was also a superb marksman, especially with assault rifles. Due to the nature of his suit, he was difficult to engage in hand-to-hand combat. Similar to other genetically modified soldiers, such as Null and Raiden, he had a barcode tattooed on the back of his neck.

After recovering from his nearly fatal injury, he was trained by the CIA as an Anti-Snake soldier, the first of his kind. Python was genetically altered and trained to be Big Boss' exact match on the battlefield, so that in case Big Boss were to turn against the United States, the CIA would have a contingency plan to easily eliminate Big Boss as a threat. Due to his brainwashing and modification, Python grew to almost a sick obsession with perfectly matching Big Boss. To keep his abilities in check, he was regularly sent on wetworks assassination missions.

During the San Hieronymo Takeover, Python once again came face to face with Big Boss, but this time as his enemy. The two fought against each other, but Big Boss eventually gained the upper hand, and defeated him.

In the Metal Gear Solid 4 Database, a family tree shows a line connecting Big Boss and Python, with a red "X", although it doesn't specify whether Big Boss killed Python or recruited him with a red "X".

Trivia

 * The player can chose to defeat Python via non-lethal methods (i.e. using a tranq gun) and a cutscene will show Big Boss helping him, and letting him join his group which would later become FOXHOUND.
 * If the player chooses to defeat Python lethally, instead of joining Big Boss, his suit will ignite and he will burn to death.
 * Python resembles the horror movie villain Pinhead, who is known for a pale head covered in needles.