Jax

Name: Jackson Briggs
Codename: Cobra
Rank: Major
Origin: Earth
Race: Cyborg
Affiliation: FBI Special Forces
Playable Debut: Mortal Kombat II
Unplayable Debut: N/A
Story: Formerly a wrestler and body-builder, Jackson Briggs joined the FBI and quickly rose to the rank of Major, while proving his talents as a search and destroy captain. He soon gained a Lieutenant Sonya Blade on his team who gave him the nickname "Jax."
There exists a criminal organization called the Black Dragon. In 1993 Kano, a Black Dragon member was taken into custody. He soon escaped. As a top priority subject, Jax was immediately put on the case. He and Sonya tracked him down with vigorous precision, but Kano remained one step ahead of them.
They finally followed him to shore, where they saw him leave on a Chinese boat. Sonya was to follow Kano while Jax went back for satellite tracking. He couldn't find them, and Sonya or Kano never came back.
Jax turned his talents into search and rescue as he set out to find Sonya. He found a secluded, mysterious, and abandoned isle. He set out to explore it, and found a massive, purple portal atop a high mountain. He went through it and found a dead world full of demons and deformed creatures. He soon found that Sonya was being held captive by a Shao Kahn, and went to free her.
He met a Chinese fellow named Liu Kang and enlisted his aid. Liu Kang explained that the only way to rescue Sonya, who he remembered from when he met her a year ago, was to enter a tournament called Mortal Kombat. He did so, but found himself fighting savage demons like Baraka, deadly and beautiful assassins like Kitana and Mileena, and a host of other Outworlders.

However, while Kahn and his minions were distracted fighting other warriors, Jax crept into Kahn's arena and broke Sonya free. He also found Kano, and offered to free him, if the thug promised to turn himself in. Kano agreed, but, after freeing him, Kano escaped through the crimson portal.
Sonya explained the entire thing. She had been captured by a shape-shifting sorcerer called Shang Tsung and was forced to compete in Mortal Kombat. Liu Kang won, but she and Kano were captured and offered as gifts to Kahn. At first, Jax questioned her sanity, but then saw people throwing fireballs and lightning and believed her.

Upon advice from their fellow Earth warriors, Jax and Sonya immediately went back to the Mother Realm and warned the American government of the threat of the Outworld. Naturally, they were hardly taken seriously. Lacking sufficient evidence, they went out to arm themselves properly. Jax sacrificed his living arms for cold, bionic implants of liquid metal that could form and shoot missiles in response to his thoughts.

When the invasion came, Jax and Sonya found themselves battling Motaro's extermination squads. After fighting valiantly against the squads, they join Liu Kang and his friends and help end Kahn's horrific rule.
Upon the reformation of Earth, Jax and Sonya have no trouble in convincing their superiors to form the Outworld Investigation Agency, and begin to open portals with science, to explore countless new realms.
While running the Outworld Investigation Agency two years later, Sonya departs to hunt down and destroy the last surviving member of the Black Dragon, a thug named Jarek. When Sonya fails to report back after a while, Jax ventures into the allied realm of Edenia to look for her, only to find it under attack by Shinnok and his minions. Now Jax is entangled in a whole new, celestial war.