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 disappeared in the early '60s, 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. Because of his wetworks assasination missions, he has had nightmares about those he killed, thus further driving him to kill Snake.

During the San Hieronymo Takeover, Python once again came face to face with Big Boss, but this time as his enemy. He explained why he has to kill Snake, and that he joined Gene's rebellion for his salvation. The two fought against each other, but Big Boss eventually gained the upper hand, and defeated him.

Weapons
Python will confront the player in battle with an M16A1 customised with an M203 Grenade Launcher. The ammunition used with the grenade launcher contains Liquid Nitrogen which will freeze the player's equipped weapons and equipment and drain their stamina upon impact and releases a blinding mist either way. Note only Python himself and nobody else including the player can use this.

Upon recruitment however the player however can use Python's exclusive LN G (Liquid Nitrogen Grenade) which is practically unlimited in supply that releases liquid nitrogen to provide quick visual cover and distract the enemy for a very short time. It is capable of freezing all the player's deployed equipment and weapons and draining stamina when in proximity of the explosion if they are not careful.

Trivia

 * In Metal Gear Solid: Portable Ops, there are two ways to defeat Python:
 * The player can choose to defeat Python via non-lethal methods (i.e. using an MK22), any CQC should be avoided. A cutscene will show Big Boss helping him, and letting him join his group.
 * If the player chooses to defeat Python lethally, instead of joining Big Boss, his suit will ignite and he will burn to death.
 * It is unknown which of the two outcomes to the boss fight is canon. Python is not mentioned again in Portable Ops afterwards, and he is not mentioned in any other Metal Gear Solid game.
 * Python resembles the horror movie villain Pinhead, who is known for a pale head covered in needles. Also, the nature of his weapons and his need of Liquid Nitrogen to survive after a mortal wound inflicted upon him resembles the backstory of the Batman villan Mr. Freeze.
 * During an unspecified time prior to his disappearance during the Vietnam mission, Python had lost to Naked Snake in a poker game, and he still owes money for it.
 * If one looks closely at the Python Lives cutscene where he warns Big Boss that leading a renegade group has burdens that, should he not be careful, he'll never defeat Gene, one can notice that the frozen hand of Snake is thawed quickly when Python touches it. This implies that Python can actually absorb liquid nitrogen to thaw objects.