That slow burn from wary allies to something deeper is basically the engine for most of the fics I've read. They're literally born into opposition, right? Protector of Earthrealm and assassin from Outworld, later its ruler. The core tension isn't just 'will they or won't they'—it's 'can they even afford to?' Every stolen moment is potentially treason. I keep seeing this theme of duty versus desire, where Kitana's loyalty to Edenia or her reformed Outworld clashes with Liu Kang's role as Earthrealm's champion.
Fics often dig into the survivor's guilt angle, too. Both have lost so much—their original timelines, their families, their mentors. They connect over that shared weight, but it also makes them terrified of losing each other, which can manifest as overprotectiveness or pushing the other away 'for their own good.' It's less about external villains and more about the internal cost of choosing each other in a universe that keeps demanding they choose their realms instead.
Honestly, the most gripping ones play with the aftermath of Liu Kang becoming a god. The new power imbalance introduces this whole layer of anxiety—can a relationship even work when one partner is literally eternal and the other is mortal? Or, if Kitana ascends too, does that shared eternity become lonely or isolating? That's where I see a lot of the quieter, more melancholic conflict happening.