A sorcerer from the Netherrealm, Quan Chi is quite easily the most treacherous character in all the games. While originally supposed to serve the Elder God Shinnok, Quan Chi's true allegiance is only to himself, and he will make and break deals with anyone if it furthers his goals. Quan Chi, contrary to most characters in the series, does not actually belong to either a mortal race or the myriad gods: he used to be an oni, a demonic torturer from hell, who eventually took a humanoid form.
Quan Chi has had a behind-the-scenes presence through a myriad of major events in the series' history. Serving Shinnok, he directly caused the deaths of both Scorpion (and his clan and family...) and the original Sub-Zero, was the one who revived Sindel in order to facilitate Shao Kahn's invasion of Earthrealm, released Shinnok from his imprisonment in the Netherrealm, and brought about Liu Kang's death during the events of Deadly Alliance. He has also betrayed every single ally he ever had at one point or another.
During the events of both Mythologies: Sub-Zero and Mortal Kombat 4, Quan Chi was working to release his master, the banished Elder God Shinnok, from his imprisonment in the Netherrealm. To this end, he also worked with Shao Kahn (bringing back Sindel for him, as previously mentioned). After Shinnok's defeat, however, Quan Chi eventually discovered the tomb of Onaga The Dragon King, which contained within his undead army, which slept in suspended animation. Wanting to control the army to conquer both Outworld and Earthrealm, Quan Chi allied himself with Shang Tsung, eventually bringing down Liu Kang together during the events of Deadly Alliance. Of course, after being victorious over Earthrealm's warriors at the end of Deadly Alliance, Quan Chi turns on Shang Tsung (with Shang Tsung doing the same, of course). They are both attacked by Onaga the Dragon King, however, and both Quan Chi and Raiden are supposedly destroyed during the events of Deception. Quan Chi did survive the events of Deception, but eventually dies along with... well, everybody else, during the events of Armageddon.
Quan Chi has an important role in the events of Mortal Kombat 9: all the aforementioned events which happen during the course of the first three games also happen during this one. It starts with the fact that he slaughters Scorpion's family to convince him to kill the original Sub-Zero, not the younger one, and it only goes downhill from there.
Big Bad Wannabe: In the original timeline after he started acting on his own (how successful he was with he plotting to overthrow Shinnok is unclear). He nearly succeeds with his plan to revive Onaga's army, only to suffer from an Eviler than Thou from Onaga himself.
Canon ImmigrantandAscended Extra: He appeared first in the Defenders of the Realm cartoon, with a whole episode where he used a magic jewel to increase the evil emotions in everyone's hearts except Nightwolf. Game-wise, he was introduced in both Mythologies and 4 at the same time as a major character.
His Leg Rip fatality in 4 and 9, where he tears your leg off and beats you to death with it, was his favorite.
In Deadly Alliance, he stretches your neck to cartoony proportions, and while he does it, it can be assumed that he's tearing your spinal kord from the rest of your nerves while keeping your head attached. It's basically Sub-Zero's head rip, but far less bloody.
Instant Expert: According to Deadly Alliance's Konquest Mode, the bulk of Quan Chi's knowledge of the martial arts comes from magic. When he was drained of his powers in the fifth plane of the Netherrealm, Quan Chi could only rely on basic Tang Soo Do attacks to ward off Scorpion.
Manipulative Bastard: Quan Chi is the one who killed Scorpion's family & clan, not Sub-Zero. He told Scorpion that it was the younger Sub-Zero, because he wanted Scorpion on his & Shinnok's side during the events of MK4.
He does it again with Scorpion and the elder Sub-Zero during MK9. In the process, Scorpion's now a MUCH more willing pawn for him, and he has also secured Noob Saibot as his servant. He might also be manipulating Raiden himself, if Raiden's visit to the Netherrealm and the Stinger at game's end are any indication.
Does some with Shinnok as well. After he has retrieved Shinnok's amulet, he kept the real one for himself and gave Shinnok a fake.
MK vs DCU also allows him to manipulate both forces of the conflict to release him from his chains on the Netherrealm. Raiden's arcade ending also gives a bit of foreshadowing to the reboot, as Raiden is forced to use what might well be Kyrptonite as a power source. Quan Chi forces him to be a servant in order to keep alive
There Is No Kill Like Overkill: His above mentioned fatality where he beats the victim with their own leg. Even when the announcer deems the opponent dead, Quan Chi ignores it and keeps "beating the dead corpse", past the screen fading to black.
This Cannot Be!: Has an Oh Crap moment upon the return of Onaga. If you listen closely, he actually says this, too.
Sareena is one of Quan Chi's personal assassins. She and her two partners, Kia and Jataaka, were ordered to kill Sub-Zero before he reached Quan Chi. They were defeated, but Sub-Zero strangely spared Sareena's life. Later, as Sub-Zero battled Quan Chi, Sareena suddenly appeared and did a Heel-Face Turn by helping him in defeating the sorcerer. After expressing her desire to escape the Netherealm with him, she's shot in the back with a bolt of energy by Shinnok. She collapses into an enraged Sub-Zero's arms and seems to die...
Shortly after regaining her human form, Sareena encountered the younger brother of the Sub-Zero she met years before. Sub-Zero granted her sanctuary with the Lin Kuei back on Earthrealm. In gratitude, Sareena pledged her loyalty to the clan, swearing to help defend it from its enemies.
In Armageddon, it is revealed that Sareena followed Sub-Zero into the Netherrealm, saving him from being killed by Noob Saibot and Smoke. She and Sub-Zero were victorious, but after the battle, Sareena lost control of her human form and returned to her true demon self. Thinking her to be a threat, Sub-Zero attacked and she fled, not wanting to harm him. However, she was later attacked by Noob Saibot, Smoke, and her former master Quan Chi, who demanded she provide them information about the Lin Kuei. At first, Sareena refused, determined to remain loyal to Sub-Zero. But Quan Chi then cast his dark sorcery upon her, returning her to her human form and then convincing her that she can never be good and that she is simply a pure evil demon. Swayed by Quan Chi's corruption, she agreed to serve him once again.
Aborted Arc: Word of God dropped a few hints that she had a connection to Reiko, but nothing came of it. All that's known is that they both were once members of the Brotherhood of Shadows.
Big Damn Heroes: If you let her live, she pops out during the battle with Quan Chi in Mythologies to deliver the coup de grace. After Deception, she also prevents Noob and Smoke from getting the jump on Sub-Zero.
Informed Ability: That being said, besides the mention of her demon form in her Armageddon bio, it's never been seen in action (possibly justified due to the above), and from what's been discerned, her true form is most likely not a Cute Monster Girl or even an attractive Beastess. Also, while likely, it's unknown if Jataaka and Kia have similar demon forms.
Dark Is Not Evil: Despite her dark appearance and insistence on continuing to wear the garb of the Brotherhood of Shadows, Sareena has proven herself to be a valuable ally of the heroes and a force for good. In a Break the Cutie moment at the hands of Quan Chi, Sareena is manipulated into believing otherwise, as seen in the quote above.
The Dragon: Arguably one to Quan Chi in Mythologies; she's the only one of the trio seen reporting to him.
MacGuffin Guardian: In Mythologies, Sareena guards one of three crystals (the other two protected by Kia and Jataaka) that, when combined together, grants access to a teleporter that sends Sub-Zero to Quan Chi's throne room.
Ship Tease: With the Elder Sub-Zero in Mythologies. With the Younger in Armageddon.
Battle Couple: Seems to be played up as the female half of one with the Sub-Zero bros. Not much happens with the elder one, as she only gets to deliver the finishing blow to Quan Chi before Shinnok "kills" her, but she comes to the younger Sub-Zero's defense to help him force Noob-Smoke to flee and in her Armageddon ending, she and Sub-Zero imprison Quan Chi in the Lin Kuei temple. Take note of how Sub-Zero revives her and how she miraculously gains freezing powers in this ending. Coincidence, right?
Interspecies Romance: She's a demoness, and the Sub-Zero brothers are mostly human, partially Cyromancer.
Loving a Shadow: Her semi-sorta there relationship with Sub-Zero the Younger could possibly be seen in this light in lieu of her previous interaction with his brother in Mythologies.
Throw the Dog a Bone: Her time with (the younger) Sub-Zero seems to be a complete 180 from the rest of her life, though.
"Farewell Thunder God, I will not fail you."
Other appearances:Mortal Kombat 4 and Mortal Kombat: Armageddon. Cameo in Mortal Kombat 9.
Fujin is one of Raiden's god-guardians of Shinnok's amulet in Mythologies, and the first of them which was challenged by Sub-Zero. He returned in 4 as one of the Earthrealm gods not being destroyed by Shinnok. He assists Raiden in his battle against Shinnok, and after his defeat, he was ascended to the Earthrealm protector status, while Raiden (who chose him as the replacement) was re-promoted to the Elder Gods pantheon.
In Armageddon, he notices a behavior change in his old friend. While Raiden was, technically, in the good guys' side, he also gained a ruthless side after realizing that Humans Are Bastards and revived Liu Kang's corpse in order to send him to do a massive manslaughter. In spite of this, Fujin allied with Kung Lao in order to find a way to save both Raiden and Liu Kang. He learns that Johnny Cage is trying to gather the Forces of Light, and there's also a mention of the brothers Taven and Daegon, whose family has been friends with Fujin over the years. Argus (their father) sent them on a quest which was corrupted by evil. Fujin then goes to search for both brothers, hoping to prevent their progress and learn the true purpose of their quest.
Badass Cape: In Mythologies. Gains it back as an alt. in Armageddon.
Sole Survivor: When Shinnok broke free of his Netherrealm imprisonment, he killed the other three Elemental Gods. A wounded Fujin narrowly escaped and would've been felled himself had it not been for the intervention of Liu Kang and Kai.
"Soon I will be free. Earthrealm and Outworld will be ours."
Other appearances:Mortal Kombat 4 and Mortal Kombat: Armageddon. Cameo in Mortal Kombat 9.
Shinnok is a former elder god and current ruler of the Netherrealm. Originally, he wanted to take Earthrealm for himself to gain immense power. To make sure he could freely enter Earthrealm without being detected, he created a special amulet which discreetly weakened the dimensional barriers. However, with the help of the other Elder Gods, Raiden discovers his plot and defeats him in battle, banishing him to the Netherrealm for good. There, he suffered constant torture until he met the sorcerer Quan Chi. With his help, Lucifer was dethroned and Shinnok became the new ruler with Quan Chi as his arch-sorcerer and right-hand man.
During the events of both Mythologies: Sub-Zero and Mortal Kombat 4, Quan Chi was working to release his master, the banished Elder God Shinnok, from his imprisonment in the Netherrealm. With the assistance of the original Sub Zero, Quan Chi managed to get the amulet and initiate Shinnok's invasion of the realms after Shao Kahn's failed attempt to conquer Earthrealm. He managed to invade Edenia and attack the heavens before Earthrealm's warriors managed to have him banished back to the Netherrealm once more by Raiden.
In Armageddon, Shinnok tricked Taven into helping him, claiming that he was no longer an Elder God for getting involved with the affairs of mortals. He wished for him to defeat the demons that inhabit his throne and he would try to locate Daegon as a reward. He successfully does the task and Shinnok tells Taven that he is most likely in Earthrealm. As he leaves, it is revealed that Shinnok was helping Daegon who was hiding in Netherrealm. In addition, it was Shinnok who alerted the many combatants to the prize at the top of the Pyramid of Argus, telling them that whomever obtained this power would be granted godlike power. His ending reveals that Shinnok created a clone of his own self to assist Daegon in Armageddon. His clone was killed off shortly after defeating Kung Lao, unable to complete his objective.
Actually a Doombot/Fighting a Shadow: According to both his Armageddon ending and 9, the Shinnok present in Armageddon was nothing more than a clone sent by the real Shinnok, who was Genre Savvy enough to not sully his hands with either the big battle itself or the in-fighting of the villains.
Batman Gambit -> Xanatos Gambit: Pulls off an epic one through both Armageddon and MK9 that would have made TywinLannister either proud or jealous. Shinnok set off the Battle of Armageddon by spreading word about the godlike power that could be gained from killing the elemental Blaze, then manipulated demigod brothers Taven and Daegon in their quest in order to guide them both along opposite paths so they would fight one another instead of working together. Through all this, he was even savvy enough to use a clone instead of personally risking his own neck. The resulting "final battle" between the Forces of Light and Darkness raged out of control until the only two kombatants left standing were a weakened and insane Thunder God (Raiden) and a vicious warrior king who the battle had left sans an army (Shao Kahn). Shao Kahn would go on to ultimately kill both Blaze (after Taven failed) and Raiden, to win Armageddon, presumably following up by conquering the realms and then going mad. With only Shinnok, Taven, Shao Kahn, and the disembodied spirit of Lui Kang left alive, nothing short of a Reset Button could stop Shinnok from creating an Enemy Mine to go after Shao Kahn and then picking up the scraps.
The Bad Guy Wins: Shinnok is literally now two moves away from becoming the evil king of the universe.
Big Bad: Of 4. If the ending of 9 is any indication, he'll possibly be this in a future game.
Bigger Bad: He was manipulating the events of Mortal Kombat 9 from behind the scenes, through his minion Quan Chi. To a lesser extent, he was also this during the events of Armageddon.
The Cameo: In the Sequel Hook of Mortal Kombat 9, suggesting that the new timeline will see some adaptation of the storyline from 4.
The Chessmaster: The Man Behind the Man to Daegon and is trusted by Taven (who is unaware that he had fallen), and pits the two against each other. He seems to have a greater awareness of what is going on than most other heroes and villans, and he chooses to use an avatar for the final battle rather than show up in person. It is implied in Mortal Kombat 9 that the entirety of that game is a result of his machinations in Armageddon. Quite impressive, though he's as much of an Anti-Climax Boss as a fighter as he ever was (even if, granted, he's not technically a boss).
Chekhov's Gun: His Amulet is technically the seventh Kamidogu. If Shujinko had collected the item and placed it on the altar alongside the other relics, it would have been sent to the Elder Gods as Onaga told Shujinko originally. When combined with the Kamidogu, its power would have allowed Onaga to reshape the realms.
Complete Immortality: The best that can be done with him is imprisoning him in the Neatherrealm and hoping he doesn't escape.
The Corrupter: Preys on Daegon's fears of being The Unfavourite to get him to kill his parents. Also subtly this to Taven, desensitizing him to murder by having him kill everything in the Spire in order to "reclaim" it—complete with repeated orders to "Eliminate" and "Destroy".
Ditto Fighter: He could also switch between the other characters' moves with ease.
Fallen Hero: His backstory. His lust for power is what caused the other Elder Gods to exile him.
Gameplay and Story Segregation: As a Fallen Elder God, he's arguably the most powerful force of evil in the entire mythos, but he has a rather lackluster record as a gameplay character. In 4, he simply copied his enemies' moves, a clear ripoff of Shang Tsung minus the shapeshifting and not much harder to beat than the other characters. He got a slightly more original moveset in Armageddon but has still yet to compare to the toughest characters in the series.
God Emperorof Evil/Satanic Archetype: Fallen Elder God, ruler of the Netherrealm, plans to rule over all of existence. Although he canonically usurped the Netherrealm from Satan (well, actually Lucifer), the dynamic is still the same.
One-Winged Angel: In Mythologies, he transforms into a scary-ass demon... thing... as soon as Sub-Zero takes the amulet, but fighting him in this form is optional (and very difficult, though it unlocks a game blooper reel), as a portal leading to the end of the game opens up anyway.
Physical God: Like the other elder gods or realm gods possesses a more ethereal form, but takes a physical one to participate in mortal events. He may have lost this ability upon his fall.
Sealed Evil in a Can: Cast down into the Netherrealm by Raiden eons before the series began, with the means of his escape (his amulet) being guarded by the four elemental gods in their Earthrealm temples. Is finally unsealed in 4.
Stealth Mentor/Treacherous Advisor: To the Elder Sub-Zero in Mythologies, thanks in part to a False Innocence Trick (this is non-canon, though; Scorpion will fight you where you encounter Shinnok instead if you killed him back in the first stage, which is what actually happened). Pulls this again in Armageddon with Taven.
Time Abyss: Existed before the universe was created making him older than millions-year old Raiden.
The Cameo: The games strongly implied that the Lin Kuei have a Grandmaster. So far, Mythologies is the only game where we see him. He finally makes a reappearance in Sektor's Arcade ending from 9, as he is Sektor's father.