Certainly, Anon! Way to ask my my favorite question XD

The Kidnapping AU (yet untitled) takes place in the second year of Newt’s possession by the Precursors, after he’s gone to work for Shao. Like “The Only Way Out is Down” it opens with the premise that he and Hermann began a relationship after closing the Breach, but unlike TOWOID, Hermann actually does something about getting ghosted by his boyfriend who now won’t return his calls and acts like a stranger to him. 
(Cut for spoilers)

So very much against Hermann’s better judgement about letting Newt go with dignity and not being a clingy ex, he finally snaps and decides he at least needs some answers from Newt about why he left, especially since the times he’s tried to drop in on Newt or meet up with him while on business in Shanghai under more casual circumstances have all been met with the discovery that Newt had a sudden, emergency “business trip”. Hermann realizes he’s being seriously avoided and decides to show up unannounced at Newt’s apartment, say his piece, and finally be able to move on. 

Err, except he doesn’t find a jerk ex who is too cowardly to break up with Hermann to his face. He finds Alice. And the fact that Newt has been possessed and essentially kidnapped himself. He finds out everything. And the Precursors are going to kill him for it. 

Newt makes a desperate deal with the Precursors to let Hermann live, unharmed and unpossessed himself, in exchange for keeping Hermann prisoner. He can never be allowed out again because he knows too much now, but Newt convinces them he’ll be utterly impossible to work with and will fight them every step of the way if Hermann dies. They accept the terms, and Hermann becomes leverage against Newt to get him to work faster and more efficiently on the plan to destroy the world.

Of course, Hermann is hardly idle, and he’s hardly helpless. Far from being imprisoned in a nightmare, he hasn’t felt this alive since Newt left. He’s been stuck in uncertainty these last years, sensing an enemy he couldn’t see. Now he knows where the enemy is, now he’s fighting the Anteverse again just like when they were closing the Breach, only now on a far more intimate playing field. He has to formulate a  plan to get them both out alive in total secrecy, given that the person who knows him best in the world is a conduit directly to the enemy. 

Which all sounds very action-packed and dramatic, but in practice, a sort of domestic calm settles over the situation. They’re together again. Newt isn’t alone in the nightmare, and sometimes it’s even possible to pretend none of this is happening, and they’re just living their lives together. 

So expect lots of domestic fluff, overshadowed by eldritch horror and a slow acting death sentence if Hermann doesn’t find a way to get them out of there. But strangely enough, even though it’s a darker, more claustrophobic situation than TOWOID, I think both Newt and Hermann wished this had happened instead, with Newt not being alone the whole ten years and finding a way to put a stop to the Precursors in Newt’s mind much sooner. I can’t wait to start sharing it with you all! But first I gotta finish TOWOID :3