Author's Note: "Aftershock" is a sequel to my fan-fics "The Girl Next Door" and "Donatello's Demise." You will probably have an easier time understanding the sequel if you read the first two, but if you don't want to take the time to, I have written a synopsis which highlights the main points of "The Girl Next Door" and "Donatello's Demise."

If you do want to read them, check out my profile for the links.

Disclaimer: Teenage Mutant Ninja Turtles, all related characters, and all derived works are the intellectual property of Nickelodeon, Viacom, Eastman, and Laird. This story is for entertainment purposes and not for monetary gain. In no way should this story be taken to be anything other than a fan-based expansion of and commentary on the original work. n00btmntfan is in no way associated with the makers of TMNT.

In "The Girl Next Door," a Japanese woman named Satou Atsuko moves into the apartment directly downstairs from April. Satou is a computer programmer, collector of traditional Japanese weapons, and an avid disciple of ninjutsu. After an unfortunate encounter with April's mutated father, Atsuko befriends April. April, who is struggling with being torn between Donnie and Casey, confides in Atsuko more and more. However, unbeknownst to April, Satou Atsuko used to go by a different name—Tang Mei. Tang Mei was the older sister of Tang Shen.

Shredder and Splinter, it turns out, had made a childhood pact when they were in school: Splinter, who was enamored with Tang Mei, and Shredder, obsessed with Tang Shen, agreed that they would help each other win the object of their affection. However, Tang Mei ended up marrying a man named Kobayashi Kenshin. Splinter accepted this and moved on—only to discover that Tang Shen had loved him the whole time. When Tang Shen chose Splinter, Shredder saw it as a violation on Splinter's part of their childhood contract. When Shredder finally decided to finish Splinter off, he decided to make Splinter suffer first. So, he captured the Kobayashis and made Tang Mei watch while he killed Kenshin and their sons Kenji and Suki. Then, he planned to capture Splinter and make him watch while he raped the woman who had once been the object of Splinter's affection. However, when Shredder failed to capture Splinter (thinking him dead in the fire), Shredder dealt with his anger by repeatedly raping Tang Mei over the one year he kept her prisoner.

After she had been captive for a year, Tang Mei managed to escape. She changed her name and sought a new life, devoting herself martial arts and learning advanced computer programming. Years later, she gets a job offer in New York and moves there—into the apartment below April's.

Donnie is working on a supercomputer to help him find the retro-mutagen, and April hopes to enlist Satou's help in the matter. However, April's life is complicated by the triangle she feels stuck in with Donatello and Casey. On the one hand, Casey makes her giddy with excitement and she really likes him (plus, there is the bonus of his not being a giant turtle), but on the other, she feels that she owes Donnie for all of the things he has done for her since they met. Eventually, after much agonizing over it, April ends up dating Casey—however, their relationship ends up being rather short-lived.

The day after Casey and April become an "item," Casey is captured by Karai, who has learned of Casey's own sordid past. As a recovering alcoholic, Casey is very vulnerable to relapse. Using that against him, Karai asks him to help her capture April. Unable to resist the alcohol, Casey agrees to help her in exchange for satisfying his addiction.

Eventually, Satou figures out that April is connected to Splinter—whom Satou partly blames for Tang Shen's death as well as her own torment at Shredder's hands. Satou is with April when the Foot Clan, using Casey's tip, track April down. Satou thinks that April is part of a trap set by the Shredder, and wanting to escape she ends up knocking April out—who is then promptly taken away by Karai.

Satou realizes her mistake and manages to find the turtles using April's t-phone. The turtles think that Satou is with the foot—and by the time they figure everything out, it's almost too late. The turtles then rush off to save April, leaving Satou and Splinter alone in the lair. Satou and Splinter reconcile.

Meanwhile, Shredder is planning to rape April as another way to punish Splinter. He almost does, but then the turtles burst in to save the day. Michelangelo is grievously injured and April is severely traumatized; however, it is unsure whether Shredder survived the encounter.

When Satou and Leonardo go to find Casey, they discover the truth. They give Casey two days to either tell April himself or to just break up with her and never speak to her again. Casey is too ashamed of the truth and so he chooses the latter option. Donnie, who learns the truth from Leo, decides that April deserves to know the truth too, since she is so upset by Casey's mysterious dumping of her.

Furthermore, April has started to suffer from PTSD; her father is the only psychologist who will believe the strange situation is true. Donnie doubles his resolve to fix Mr. O'Neil so that Kirby can help April recover. Donnie swears to April that he will never rest until he finds a cure. Then, to his surprise, April declares that she loves Donnie and they kiss.

The story ends with Satou Atsuko reclaiming her identity as Tang Mei. The turtles adopt her as their aunt. She decides that she will finally heal from her old traumas and resolves to help April overcome her PTSD.

In "Donatello's Demise," we see April and Donnie's relationship off to a rocky start as she goes through PTSD and he works feverishly to perfect the retro-mutagen. Mei still feels a little unsure about who she is, but spends a lot of time with her new family, and steadily makes peace with her past. She helps April with coping and assists Donnie with his super-computer project so that he can develop the mutagen.

At Michelangelo's suggestion, Splinter asks Mei if she would like to move into the lair with them. Mei thinks about it for several days and then agrees. The super-computer is finished, and now Donnie can work on the retro-mutagen in earnest.

Things take an unexpected turn when April is approached at school by Casey, who has finally decided to stop avoiding her and tell her the truth. Unfortunately for him, April already knows, and she is furious with him. Nevertheless, talking with him triggers a panic reflex in April, and she spends the rest of the day terrified that this is all a ploy so that Shredder can get a hold of her again. The symptoms of her PTSD and this fear make her lose control, and she ends up going to her apartment and tries to kill herself by slitting her wrists.

She is found later that evening by Mei and Donnie, who rush her back to the lair. She has lost a lot of blood, and because of her unique DNA, there is nobody in the city who could be a proper donor. Donnie breaks down, out of ideas – fortunately, Mei steps up to the plate and suggests that they use Donnie's equipment to synthesize blood for April. They are successful, but April is in a coma for seventeen days.

During that time, Donnie perfects the retro-mutagen and they test it on a hostile to see if it works on a complete organism. After turning Fishface back into a human, they realize that it's totally safe and plan to use it on Kirby.

After the test run, the turtles get back to the lair to find April awake. Everyone is ecstatic, except that Donnie has an unexpected reaction of anger at first. After a while, he is able to forgive her, and for a little while, it looks like everything will go back to normal.

Then, when Donnie and Mei are trying to administer to retro-mutagen to Kirby, Donnie accidentally injects himself with it and gets turned back into a regular turtle. Splinter withdraws from everybody; Mikey has a spectacular breakdown.

Unsure of what to do and unable to turn to Splinter for help, Leo steps up to the plate and decides on a course of action. He decides that they will use Karai to communicate with the Kraang for them, since the Foot and the Kraang are sort of frenemies. To reach Karai, they decide to use Casey.

Unbeknownst to them, Karai has been having dreams about Mei ever since she first saw her – she doesn't know who Mei is, but feels like she should know her. She offers Casey anything he wants in exchange for more information about Mei, but he refuses to help her. Nevertheless, she leaves him with a number "just in case," and he finds himself unable to throw it away.

When the turtles approach him, Casey provides them with the phone number and they contact Karai. The plan is set in motion, and Karai begrudgingly agrees to help them. However, Shredder's scouts have gotten pictures of Mei. He explains to Karai who she is, lying and saying that Mei's husband helped Splinter kill Tang Shen. He explains how he killed Mei's husband, and that Mei is probably looking for revenge. Furious, Karai promises that she will capture Mei so that she will no longer pose a threat.

After setting up a trap for Mei and capturing her, Karai refuses to listen as Mei tries to tell Karai who she really is. Karai believes she is lying and ends up delivering Mei to Shredder, but Karai feels incredibly guilty and doubts herself.

Shredder, being the terrible excuse for a human being that he is, gloats over Mei and asks her where he can find Splinter and the turtles. When she refuses to help him, he beats her and the scene cuts away, but it is obvious as to what is happening. In the meantime, Baxter Stockman is hacking into Mei's phone, and is able to trace the location of the lair from there.

When Mei's phone is hacked, it sends out an automatic distress signal with coordinates. Kirby, who has been un-mutated, helps them figure out where to go – Shredder's lair. Splinter, Leo, Raph, and Mikey rush off to the rescue, leaving April, Kirby, and Donnie in the lair. Kirby has purchased a gun off the black market so that he can protect April; when April points out that guns are illegal in New York City, Kirby quips that so are sodas larger than 16 ounces.

While Splinter and the turtles arrive at Shredder's lair and rescue Mei, they discover that Shredder has already left and has gone to the lair. Splinter sends the turtles ahead and he stays behind to help Mei escape.

Shredder and Karai arrive at the lair and find it deserted. They venture in slowly and hear a gunshot. Karai sees April in the dojo and runs in to capture her, while Kirby keeps shooting at Shredder (and missing.) April and Karai struggle – Donnie helps by biting Karai on the Achilles' tendon, and when she is thrown off balance, she bumps into the picture of Splinter's family. She has the horrible realization that Mei was telling the truth.

Leo, Raph, and Mikey arrive at the lair and immediately attack Shredder. Hearing sounds coming from the dojo, Leo runs in and finds Karai staring at the picture. He asks if she will help them. She says she will, but only if she gets to kill Shredder. They all head back out into the main lair, where Shredder is unfortunately gaining the upper hand. Sometime during the fray, Kirby gets thrown across the room and lands next to the turnstiles; his gun lands next to him.

Splinter arrives just in time to get everyone out of a sticky spot, leaving Mei near the turnstiles. However, Shredder grabs hold of Karai and threatens to kill her unless they let him leave.

Mei grabs Kirby's gun and fires twice. The first shot knocks off Shredder's helmet; the second kills him.

Afterwards, Kirby and April take Mei to the hospital, since none of them have the expertise to treat her extensive injuries. When April and Kirby return to check on everyone, they report Mei's injuries. Karai asks to talk to April, and April extends a hand of friendship, much to Karai's surprise.

They all put together a 'welcome home' party at Mei's apartment. Karai finally gets to talk to Mei again, and she is shocked when Mei forgives her.

Karai decides to return to the Foot Clan to work under cover to tear the rest of the Foot Clan down as well as try to get help from the Kraang.

The story ends with April promising Donnie that she will wait for him, no matter how long it takes.

(Oh yeah, and something I forgot to mention during this synopsis is that Mei and Splinter sort of kind of might be forming a relationship - they know they care about each other in more than a familial way, but it's complicated.)

On to the sequel!