In your fic, why didn’t Celebrimbor tell Sauron what they had been to each other? If he had, how do you think Sauron would have reacted? Or if he showed him the memory of being rejected? Also, why do you think Celebrimbor would make a bad parent?

Celebrimbor is uncertain how Sauron would react and feels no obligation to tell him. As for Sauron's reaction, well, he is remembering more and more and I hope you'll forgive me if I defer on those questions and answer them in the next chapter.

With regards to Celebrimbor as a parent. I’d like to caveat this by saying I am talking about my personal interpretation of the character (I mentioned it in a headcanon post) and my personal interpretations of themes in canon. I don’t mean to come off as authoritative or invalidating of other interpretations here and apologize if I do. But yes, I don’t think Celebrimbor wants kids or would be great at raising them, and moreover I think that, if you write him as a Feanorian, he thematically can’t have kids.

One of those themes that is important and interesting to me is dissolution of family, that Finwe had such a large family and it was whittled down to nothing (likewise Elwe’s family, though it’s smaller). Maeglin never meets Fingolfin, Elwing is a war orphan, Finduilas the spring leaf of the House of Finwe dies young, Elrond and Elros know no grandparents, Celebrían has a huge family on both sides but knows only three of her distant cousins, and two of them die in her lifetime*. And I think this needs to apply even more (sevenfold?) to the House of Feanor: it falls apart, it dies, the deeds that led to the Feanorians being cursed make its destruction inevitable because of story logic. I bounce off OC Feanorians the same way I bounce off AUs where everything goes well: “that’s not how Arda works,” I think; even AUs with a happy ending need some tragedy; even fix-its need to have a cost. If Celebrimbor is a Feanorian, there’s a way in which I think he can’t have a kid? He’s the only one of the Feanorians who has a heroic death, the only one with a noble (if terrible) death, one of only two killed by the actual enemy (not killed because they are the enemy), he’s the best of all of them by far... but he has to die, and all that survive him a Great Work. The Feanorians bear no fruit - that which survives them are the Silmarils (made before the Oath) and the Rings (made by someone who didn’t swear the Oath). Celebrimbor is innocent of the sins of his family, but he can’t escape story-fate.

*Elrond, Gil-Galad, and Celebrimbor being the cousins - I’m not counting her parents or children, even though they are also cousins given the convoluted family tree! I prefer Oropher and/or Amdir not to be related to Celeborn. I do think it would be mentioned if either of them were related to Thingol and let's have some elves in positions of leadership not related to Finwe and/or Elu: surely there were some people in Middle-earth who weren't =P

This is also why I don’t go for any OC Finweans in Middle-earth. The Houses of Finwe and Elwe fall apart. They are diminished, in the literal sense of getting smaller and smaller. Then comes to the re-knowing of family in Aman once people start showing, which I also think is interesting esp since I headcanon that the 2nd Age people and Finduilas are reborn first.

As for why I don't think C would be a good parent, I am talking about my version, not anyone else's. But I don't think he wants children (which is not to say that parents who end up having kids despite not wanting them can't be good parents!). Rather, I think he'd resent them in some way for taking his attention away from his work (can’t spend a week locked away in a workroom if you need to feed a baby) and not know how to act around them. He’s far more emotionally literate than his parents (not difficult), but he’s even more unable to explain things on a child-appropriate linguistic level (though perfectly good with adults). He also tends to be sharp, isn’t inclined to niceness (kindness and pity yes, but there’s a difference between that and nice - a bit like Gandalf in that way), thinks he’s almost always right, and he’d probably be fairly critical despite knowing he shouldn’t be.

Finally, kidfic as a genre does nothing for me? I get its appeal and I’ve liked a couple, but it’s not for me personally.