Only Sane Man: Nitara and Shang Tsung seem to be this on Raiden's side.
O.O.C. Is Serious Business: Liu Kang and Kitana immediately know something is really off about Raiden when he tossed the still-living head of Shinnok at their feet during his threat to destroy all realms. When Cassie and her team later drop by in the 1st chapter, Kitana explains the goings-on about Raiden following his corruption. Their suspicions about Raiden's corruption are confirmed when Kotal Kahn and Fujin sought an alliance with them in order to stop the power-mad thunder god.
You know you're evil when Hanzo bluntly states that he'd rather work for Quan Chi (albeit a brainwashed one) than you, Raiden. Cue Hanzo's HeelFace Turn.
Oh, Crap!: Kitana and Liu Kang when Raiden drops Shinnok's head at their feet.
Skarlet and the Red Dragon when Torr awakens from his coma to save Ferra and attacks them.
Daegon when Delia, unable to kill her own son, allows Jade to take control of their shared body. The demigod immediately gets his ass handed to him by the former revenant before Raiden arrives to collect his Red Dragon minions.
Kano upon realizing that Daegon, whom he is mocking, is standing right behind him.
Everyone when Shang Tsung returns.
Also occurs in chapter 54, when everyone realizes that Raiden was snooping on their conversation, and when he declared war on his ex-allies.
Our Vampires Are Different: Namely Nitara's species are called Moroi belonging to the realm of Vaeternus, a world that was long conquered by Shao Kahn. They are only weakened by Earthrealm's sun, and apparently only wooden stakes and the holy sword Ashrah carries can kill them.
Sonya's obsession with her job hasn't given her the best relationship with Cassie, but they still love each other very much. Sonya goes Mama Bear and nearly loses her grip on sanity when Cassie is kidnapped by Raiden and Kano, but Johnny manages to keep her sane until their daughter is rescued.
Kenshi's abandonment of Takeda has damaged their relationship greatly, but they have somewhat reconciled and are growing closer now that Kenshi is working to become a better father to his son.
Kano kidnaps and tortures his son Kevin, whom he conceived through rape, and shows no concern whatsoever for the boy's fate, calling him a weakling and a waste of space. In return, Kevin hates Kano with a burning passion and it is only his desire for revenge that keeps him from allowing himself to die.
While Argus wasn't abusive to his children and was very supportive of Taven, he treated his two younger sons Daegon and Rain like dirt. Daegon hardly received any attention or praise from Argus and had to turn to Caro and others for a father figure while Rain, who was conceived through infidelity, was exiled from Argus's family and unaware of his true paternity until Raiden told him after Shao Kahn's death. Argus even went as far as to tell Daegon to his face that he was ashamed to call Daegon a son moments before the demigod killed him. As a result, both Daegon and Rain are extremely bitter and angry at their father, with Rain seeing his deceased adoptive father as his true father.
After Taven learns that Argus treated Daegon and Rain like dirt, he begins to see his father as a Broken Pedestal alongside the Elder Gods (including Shinnok).
Kira's parents sold her into sexual slavery when she was nine years old. After killing her slaver several years later, she hunted her parents down and killed them.
Jade's parents gave her as a gift to Shao Kahn as a sign of loyalty to the emperor when she was very young.
Ruby's father is said to have blamed her for her mother's death and hated her deeply.
Posthumous Character: Though Shinnok doesn't appear in the story, he does make a lasting impact by twisting his Arch-Enemy Raiden into something just as evil as himself.
Argus is also this, as he appears in flashbacks and is mentioned several times by his family and old allies.
The Power of Blood: Skarlet is literally made up of blood and gets stronger by absorbing the blood of others into her skin while Nitara is a vampire.
Pragmatic Villainy: Shang Tsung - he's got a big Chronic Backstabbing Disorder, as he only joined Raiden's faction for his own agenda. And Raiden is so concerned with his former allies that he does not see Shang preparing to stab him in the back, just as he did in the original timeline (with Quan Chi, Shao Kahn and Onaga).
Raiden's invasion of Outworld has led Kotal Kahn to pursuing an Enemy Mine situation, forcing him to ally with groups that would not support the corrupted thunder god's actions, and as well as revenants who have their own individual beef with Raiden (though they have been since restored to life). Despite their own individual flaws, it's the best group Kotal Kahn has mustered so far.
For Raiden, he has assembled the worst of the worst to fight for him, of which includes traitors, zealots, criminals, backstabbers, constructs and murderers.
Royals Who Actually Do Something: Kitana, Sindel, and Jerrod are the royal family of Edenia. Jerrod is a bit excused since hes Sharing a Body with Ermac but he still helps. Kitana will take over as Queen of Edenia once the war is over and Sindel acts as regent in her absence during the tournament.
Kotal Kahn is the first ruler of Outworld who actually cares about the realm.
Fujin is a divine example, as Raidens replacement as Earthrealms protector.
Taven and Delia, son and wife of Edenias Protector God Argus, have very active roles.