Once, centuries ago, an infant succubus was adopted by Belial Aensland, the ruler of Makai. Her power made her a worthy heiress to his throne, but he also knew that her power could intoxicate her. So, he divided her power into three. The succubus, whom he would dub Morrigan, would keep one third of her power. Belial would keep another third in trust until he felt she was ready for the responsibility, or when he died, whatever came first. And another third, he sealed within a pocket dimension.
Belial was unaware that this particular third of Morrigan's power would soon develop its own sentience, a life of its own. In most timelines, this isolated third of Morrigan's power would be found by Jedah Domah, a rival to Belial's throne. This mass of energy with a personality would be given a body, and a name, Lilith.
However, in this timeline, the power that would become Lilith was found by a very different party indeed. A group of Unspeakables from the British Ministry of Magic would find the pocket dimension by accident. And that power, and the sentience that came with it, entered into a young Unspeakable by the name of Lily Potter, who was unaware that she was pregnant at the time. As a result, Lily's unborn child had two entities within him, and a single soul.
The story picks up a decade and a half after events conspired to kill Lily Potter, her husband, and elevate her son to one of the most famous people in Magical Britain. During the fateful night Harry is forced to witness the resurrection of his nemesis, Lord Voldemort, his imaginary friend, Lilith, soon enough proves to not be so imaginary after all...
Never Tear Us Apart provides trope examples of:
- Adaptational Badass: Being bonded to Lilith, Harry shares her power, giving him a boost to not only his magic, but also to his physical capacities. However, Morrigan notes that Harry's body isn't physically fit to use the power at will, so she takes to train him so he can master it.
- Adaptational Curves: While Lilith is flat-chested in the videogames, and even though Morrigan teases her about it, Harry's thinks her assets are pretty generous already, mostly because her apparent age is the same as his.
- Anything That Moves: Morrigan, being a succubus, is very open about copulating with men and women. Or Soul Bees, as long as they don't implant larvae on her.
- Assassins Are Always Betrayed: B.B. Hood is very much aware of this trope, as she's had people thinking that they wouldn't have to pay her if she was dead. Of course, no one of them would live long enough afterwards.
- Badass Normal: B.B. Hood is a muggle, but she packs enough heat to fight Darkstalkers of Morrigan's caliber on equal grounds. She even kills a Death Eater to prove that she means business.
- Big Sister Instinct: Having to act as a guardian to Harry and Lilith, Morrigan quickly develops this for both of them.
- Blue-and-Orange Morality: Belial admits to Harry that Darkstalkers not always act in a manner humans would consider moral, while Morrigan says that she only does what she enjoys, and doesn't attack humans only because she finds them too interesting.
- Bring My Brown Pants: When Draco, Crabbe and Goyle come to taunt Harry at the train over Cedric's death, Morrigan gets them to crap their pants with her sole presence, before they run away in terror.
- Combat Sadomasochist: Both Morrigan and Lilith are this. The latter, being bonded to Harry, can transfer her pleasure to him.
- Comes Great Responsibility: Dumbledore even cites the Trope Namer upon realizing the kind of power Harry now has thanks to Lilith.
- Cool Big Sis: Morrigan at least tries to play this role for Harry and Lilith. Lilith considers her embarrassing at times, while Harry calls her a sadist during their training.
- Dark Is Not Evil: When they arrive at Grimmauld Place 12, Sirius is surprised that Morrigan doesn't like the place's darkness. Morrigan explains that darkness "should feel warm, encompassing, like a blanket", instead of being grotesque and stagnant like the Blacks' house.
- Eating Optional: As Lilith sustains herself through Harry's magical power, she doesn't need to eat, but she still enjoys it when Morrigan sets up a dinner for the two of them.
- Everyone Has Standards: Even though Lilith admits to being a masochist, the Cruciatus Curse is a bit too much for her.
- Familiar: Lilith is this to Harry. Dumbledore remarks that since ancient times many wizards have tried to get Darkstalkers as their familiars, without much success.
- Fantastic Racism: Very much present. The Wizarding community isn't very fond of Darkstalkers, while the latter don't think much of humans, though some like Belial prefer to just stay away from them while Morrigan finds them interesting. Conversely, B.B. Hood hates both Darkstalkers and wizards, the former due to her Freudian Excuse of her family being killed by them, and the latter because she considers them stupid and old-fashioned.
- For Want of a Nail: Harry being bonded to Lilith, and her subsequent release causes a lot of changes.
- Lilith at one point casually mentions having "eaten" a soul fragment. Dumbledore deduces this means she unwittingly destroyed the Horcrux within Harry.
- Morrigan and Lilith move in with the Dursleys, who grudgingly agree to let them in their house. As a result, Harry copes better during that summer despite everything he knows is going on.
- The Dementors' attack to Privet Drive gets botched by Morrigan taking Harry and Lilith to Makai before they come close, and one of them getting killed by B.B. Hood. As a result, Harry doesn't get dragged into a trial for underage magic.
- Dumbledore installs Morrigan as a Defense Against the Dark Arts teacher before the Ministry can appoint Umbridge for the position.
- Dumbledore gets in touch with Hsien-Ko and Mei-Ling for their expertise in dealing with immortals and undead. With their help he discovers Salazar Slytherin's locket is one of Voldemort's Horcruxes, as well as confirming the existence of many others.
- Inevitable Mutual Betrayal: B.B. Hood has been hired to kill Lilith and capture Harry Potter for Voldemort and the Death Eaters, who plan to kill her once she fulfills her end of the bargain. She, for her part, is very much aware of this and plans to milk all the money she can of them before she offs them herself.
- In Spite of a Nail: At the point the story begins, it's inferred that Harry's first four years at Hogwarts (and most of his life prior to that) went pretty much the same way as in canon, barring the fact that he had Lilith to comfort him during hard times. Afterwards, some important events also play the same, including:
- Barty Crouch Jr. receiving the Dementor's kiss, and the subsequent denial from Cornelius Fudge that Voldemort has returned.
- Despite Dumbledore finding a Defense Against the Dark Arts teacher, Fudge manages to install Umbridge into Hogwarts as High Inquisitor.
- The Ministry of Magic begins their smear campaign against Harry and Dumbledore, and the latter assembles the Order of the Phoenix to begin the fight against Voldemort.
- Horny Devils: Morrigan and Lilith, being succubi and all.
- Incompatible Orientation: Apparently, Morrigan had an encounter with Albus Dumbledore when he was younger, but as he was in love with Gellert Grindelwald, he showed no interest in her, much to her dismay.
- Interspecies Romance: Harry, a human wizard, and Lilith, a succubus, with a bit of Magic Contract Romance thrown into the mix. Felicia, a catwoman, wishes she had this with the werewolf Jon Talbain, but he only sees her as a friend.
- Nice Job Fixing It, Villain!: Par for the course for Voldemort. His decision to torture Harry using the Cruciatus Curse before killing him ultimately cracks the barrier holding Lilith's power, releasing her and giving her a physical body.
- Not-So-Imaginary Friend: The whole story's premise. Before she was released, Harry thought Lilith was just his imaginary friend.
- Only in It for the Money: As long as she gets paid, B.B. Hood always gets the job done. The only times she does work for free is when people backstab her (and then she ransacks them anyway).
- Our Werewolves Are Different: Remus Lupin meets with Jon Talbain, who once offered him training to control his inner wolf, and he's willing to take it now.
- Shipper on Deck: Morrigan is very encouraging of Harry and Lilith being together.
- Strong Family Resemblance: Dumbledore quickly notices how much Lilith looks like Morrigan.
- The Tease: Being a succubus, Morrigan loves being this, even with people she does not seduce. Lilith is no slouch in this department, although she mostly acts this way only to Harry.
- Threat Backfire: When Draco goes with his usual "I'll tell my father about this", Morrigan tells him to please make sure of it, so he knows that crossing her will be the last mistake he'll ever make.
- Unskilled, but Strong: Harry and Lilith share a third of Morrigan's power, but still lack the experience to properly use it at will.