Oh man, y’know for Bagginshield I had such specific headcanons for smut, but with Newt and Hermann it’s more dependent on the kind of story the author is trying to tell? 

(Cut for NSFW discussion but also just general headcanon rambling)

I like reading fics where Newt’s a bottom, I like fics where Hermann strictly prefers to bottom, and I like fics where they switch! I like fics where they’re both kink monsters who have racked up considerable experience, and I like fics where one or both of them are secretly virgins. I don’t personally like fics with lingerie or cross-dressing/feminization but that’s a unique squick of mine that has nothing to do with the quality of those fics and even then I’ll dip into those tropes for good Newmann banter. 

For my own fics I tend to default to, “They’ve each had a few partners before, so they’re not inexperienced, but no one who really stuck.” A big part of that for me was the letters: after age 25/26 when they began to exchange those letters, both of them had a very fixed idea of who they wanted to be with (each other) and heavily romanticized the other and secretly pined after the other as their soulmate, to the point where any relationships they had limping along finally bit the dust, and they both struggled to form meaningful relationships with anyone else after, because everyone else just felt dull in comparison or more specifically “Not Hermann/Newt”, respectively. Basically: they ruined each other for other people (and I can so easily see both of them biting that back as an insult they’d like to fling because it would reveal too much, but both harbor a simmering resentment in the lab that they just can’t quit this annoying asshole, even when everything became a disaster after the letters, and they’re both pissed that even now that they “despise” each other they still can’t pull their romantic lives together and are still hopelessly pining, which in turn feeds the heat of their sniping). 

I headcanon predominantly (as in, I’ll switch it up for a fic, but I have a strong sense of a “default”) that Newt had trouble holding down long-term relationships even before the letters because he’s flighty, easily distracted, and hard to deal with it, to the point where even he was self-aware of those traits. It’s one reason he attaches to Hermann so strongly: even when he was at his absolute most heinously annoying, Hermann stuck around. Maybe not in a “relationship” sense, but he didn’t request a transfer or even a separate lab. Hermann clearly wants to be around Newt (maybe on a perverse and masochistic level, lol) in a way Newt does sincerely appreciate. Even Newt’s mother didn’t stick around, and we see no sign of him having other close friends or partners, so I do think his teasing of Hermann is to some extent a guy with chronic abandonment issues perversely needing to constantly test the boundaries, “If I do THIS will you leave me?? What about THIS??” and gaining comfort when nothing is enough, knowing it’s toxic and counter-productive behavior, but not really being able to stop because he needs to either lose people on his own terms or know they’ll never leave him no matter how he acts out. Which could very well stem from being the youngest, most immature person in the class at school too. (Oh, and on that note, I totally agree with other writers that Newt has a serious “strict professor/librarian” kink thing with figures of authority that dominated his youth which feeds into his sincere attraction to Hermann on a primal level). 

I do think Newt’s dossier statement that his dating preference is, “anyone who will take him” is not narrator-voice/word-of-god speaking in the third person about Newt, but literally something Newt is self-aware about for himself. Unlike a lot of the fandom I actually headcanon Newt as truly pansexual rather than bisexual based on that quote: genitalia does not matter, only someone’s willingness to be with him does. I see him as totally game to fuck aliens regardless of anthropomorphism or genitalia, inspired by Star Trek, Mass Effect and sci-fi in general.  THAT SAID, I actually don’t personally like to write Newt as the “Kaiju fucker” because I actually like to credit his statement about, “I don’t love them, I study them,” as sincere, and not deflecting a fetish. LOL, I don’t think Newt would ever deflect from talking about his fetishes if they came up, he seems very open and honest in that respect SO, if we break down that statement, it strikes me as something he’s thought about. I strongly headcanon that when Kaiju first showed up, Newt was down to fuck if they had turned out to be sentient and benevolent and able to give consent. The fact they’re trying to destroy our world and can’t be reasoned with is why he’s not a Kaiju fucker and knows he isn’t, not the idea of fucking aliens in particular, but he’d never fuck these aliens, specifically. Because either they have beast-like intelligence and can’t give consent OR they DO have intelligence and they’re malicious. He’s outraged at the implication that he’d fuck Kaiju just because he’s obsessed with studying because HE’S THOUGHT ABOUT THIS, OK, AND NO, JUST NO. (Also it adds a delicious level of tragedy that this reputation of Kaiju fucker comes back to bite him so hard in Uprising. I truly believe any vestige of positive fascination he had for the Kaiju was dead by the end of PR1, but the legacy of it made his being controlled and destroyed by them “unsurprising” in a really tragic way). 

IMO, to turn to Hermann: he’s strictly gay but has a lot of baggage attached. I can totally buy Vanessa being someone he was with at some point, maybe even “married” to on paper, but I see it pretty strongly through the lens of a relationship with a like-minded woman who was probably a close friend that his family encouraged because his father  was homophobic and encouraged his son to marry this woman to make him proud, in denial of his sexuality (whether or not you headcanon them as actually getting married). 

I think Hermann has a lot of internalized fears around homophobia because of his father and may even resent Newt’s more progressive upbringing that Newt never had to wrestle with those demons and was always comfortable in his sexuality and free to explore and experiment openly around his family. That said, I do think Hermann switching side away from his father to support the Jaeger program instead of the Wall allowed him to shed a lot of that baggage: once he made that stand against his father, and realized his father wasn’t infallible because he had so clearly taken the wrong side in this war, it freed Hermann up to be more decisively his own person. Rebellion is exciting to Hermann, but also still very scary (as seen in PR1 and 2 when he tries to be a badass and actually does quite well!). That includes him being completely open with his sexuality by the time we see him in PR1. 

Last note on sexuality and fetishes: but I think they’re into each other, totally. Physically, mentally, circumstantially. It’s gross to everyone around them how into each other they are, lol. It’s the source of a lot of their anger in their old fights that they had all this tension between them. Newt is sincerely into Hermann’s whole professorial “look” even if he teases about it, he’s deeply respectful of Hermann’s disability and it would be antithetical to his very existence to bring it up negatively. He thinks Hermann is as hot as it gets. They mock each other’s intellect but from a place of them being the only ones allowed to do so because they’re on the same level and it’s so lonely at the top that they deeply appreciate, even if not especially through the mockery, how rare this level of intellect is and they cherish it in one another. 

Likewise, Newt’s entire look is based around rebellion, and Hermann I think has a secret, buried kink for display of rebellion in others because it was so forbidden to him growing up. It’s exciting. Newt’s tattoos’, his barely-professional clothes, his rockstar attitude, even the fact he’s got the pudge and doesn’t care what other’s think about it, are deeply exciting to Hermann in ways that he could never have for himself. Newt is extremely attractive to him, physically and mentally, if exasperating at times for not having better self-preservation instincts, but again, that’s part of the charm that Hermann will never admit to aloud. 

Long story short, I think they’re well matched and deeply in love. They fulfill things the other needs like someone who is stable and sticks around for Newt, and someone who breaks him out of his shell for Hermann. I just love the a lot, ok?