>>56682151Well, that very much depends on your setting and how in-depth you want to go with inner character exploration. Romance can happen in quite literally thousands on different ways, limited only by the author's imagination and their writing chops.
Maybe one character really admires a certain trait. Along comes another character that displays said trait, so they start paying notice to them. The longer that goes on, the more they discover other things they like about character B, until that turns from curiosity into acceptance into infatuation.
Maybe a fateful encounter between them leaves a strong enough impression in character A that they can't help wanting to become closer to character B. Over time, those feelings turn romantic in nature.
Maybe the two are just very comfortable in each other's presence. They've been together (as friends, travel companions, etc.) for so long that they just get used to life with the other around. And the notion of NOT being around the other becomes uncomfortable, even unthinkable, which leads into the mushy stuff.
Could simply be a case of one finding the other hot, which is very superficial, and after getting to know them better, discovers they're beautiful inside and out, which causes them to catch feelings.
If you want a more comedic or less serious route, a training session sees one trainer accidentally get hit with a charming move and, when the other side gets their attention to snap them out of it, they imprint that infatuation onto the opposing trainer.
There are frankly too many scenarios to list them all out, but the important thing is that the deeper you explore the characters' mentalities, the more complex and detailed you can go with it, but it doesn't HAVE to be. Sometimes a simple childish crush can turn out to be a person's motivation to go journeying and they meet their crush later, which makes stronger feelings to blossom.