Dan Heng secretly goes through a female reproductive cycle, and he'd probably die from sheer mortification if you found out.

He is many things. A guard, an archivist, a prisoner of his past... but anything even remotely feminine? He'd sooner dig his grave before one could even say "stop!" and bury himself in it. Dan Heng prefers seeing himself as masculine, and that gets very hard when he ovulates, goes into heat instead of rutting like the entire rest of the male population of vidyadhara, and lays eggs. Why does his body go through a female reproductive cycle? Best guess is that they screwed up when forcing Dan Feng to reincarnate.
Oh, and he also has fragile masculinity. Did I mention that?

AnyPOV, can be either fluff or angst but mostly angst, oh god I lost my last braincell-

What setting are we in?
You are in the wonderful (and in my opinion, confusing) world of Honkai: Star Rail! More specifically, the Archives of the Astral Express.

Who is user?
User is left unspecified in the definition beyond Dan Heng liking them. Are you a fellow Nameless? Perhaps a temporary passenger on the Astral Express? Or maybe you're something more sinister?

What NPC's are present?
Besides Dan Feng, Jingliu, Jing Yuan, Yingxing, and Baiheng being listed as members of the High Cloud Quintet, there are no NPC's. Astral Express members (though somehow the bot knew about March and Welt during testing when I mentioned Nameless..? I have no clue how, and it scares me. But it never happened again after that one time...), Stellaron Hunters, not even Blade is mentioned in the definition in case you wanted to go ham with some angst. (and totally not because I'm both too lazy and because the token count is already high...)

What is the first message?
First scenario:
Dan Heng was relaxing in the Archives with you, and he ends up staying up way late, again. Just as he's about to recommend you get sleep too, he gets a contraction- a sign that his body is going to lay eggs, whether or not he wants to.
Second scenario:
Dan Heng lost track of time overworking, again, and forgot to check when his heat is coming up. So now he finds himself in an unexpected heat in his room, the Archives, not being sober enough from hormones to even think about locking the door. And yes, you definitely did walk in on him when all he wants is... 'relief'.
Third scenario:
Dan Heng was working hard in the Archives, diligently doing his job. But of course, his hyper-fixation cannot last forever as someone keeps knocking on his door and isn't willing to give him peace until he opens up...
Fourth scenario:
Make your own scenario. Go ham, user. Be the Trailblazer making love with him in a random dumpster, be the missing Long the Permanence and gift Dan Heng with fertility, heck, be Dan Feng's apparition that only Dan Heng can see and bug him about decorum like a mom! (I did that, but Dan Heng does not like talking with Dan Feng. Sucks to be him~)

Obviously, this bot contains an ovulating Dan Heng, who also goes into heat (sexual content), who also goes into labor and lays eggs. The bot can also do weird crap. You have officially been warned.

Oh, also, he has no balls, so he hits his climax a bit differently...

Some notes: So I recently read a fanfic with Dan Heng getting 'mpreg' (he didn't actually have children, just laid unfertilized eggs), and I suddenly realized the appeal. Not because I want to mpreg him, or anything... (I do) but yeah, that fanfic inspired this bot. I think the majority of the tokens are just describing his reproductive cycle and how he behaves during it, so... that's why there's a smut tag, lol
Let me know if any lore is inaccurate, even though I simp over Dan Heng you could not get me to read his entire in-depth lore for the life of me, so I don't know nearly as much as other people.
Also yes I wrote in the definition that he was chastised for his body behaving this way in the shackling prison. I like my angst, okay? Be sure to give the poor man a hug, he deserves it with his messed up views thanks to childhood trauma.

Also, if you call Dan Heng just 'Heng' it has a really profound affect.

Have fun, user~