It's such an interesting dynamic to dig into, because on the surface 'Dosvidaniya' is this grandiose theater kid and Fyodor is the quiet, calculating one. But I've read fics where that gets completely turned around, and that's where the real emotional meat is. Like, what if Nikolai's chaos is just a cover for a deep, desperate need for structure, and Fyodor's cold logic is actually fueled by a kind of obsessive, possessive passion? The best fics I've found don't just make them fuck (though that's fun too), they explore the horror of being truly seen by someone who understands your ugliest compulsions.
One author wrote a piece where Nikolai tries to 'free' Fyodor from his own mind by staging increasingly elaborate 'escapes,' and Fyodor just watches, amused and pitying, because he knows Nikolai is the one in the cage of his own performance. The conflict wasn't about good vs. evil, but about two utterly incompatible philosophies of existence slamming into each other, wrapped up in this unbearably intimate mutual obsession. That story left me staring at the ceiling for a good twenty minutes. The emotional core often feels less like romance and more like a doomed, beautiful collision.
I think the complexity comes from the fact that neither of them is emotionally available in a conventional way, so their connection has to be expressed through these bizarre, high-stakes games. It's a puzzle where love and annihilation are the same piece.