I have a curious thought that came to me as a combination of previous things that appeared on the forum:
Do you think that the lack so far of a non-straight KISA (love the acronym!) is largely due to other tropes in writing characters? The three most prominent examples I can think of is the player-character as the only one with agency, the player character as the strongest and most emotionally balanced character in the party, and the fact that flirting from NPCs is more accepted in a straight context.
The first example is easily seen from the fact that in pretty much all games (especially Bioware games) the player-character is the only one who initiates and confirms relationships by flirting first or blatantly flirting back. Obviously this is preferred by most players, but part of the KISA archetype involves assertiveness and romantic gallantry, which kind of imply a bit of pro-activeness in courting (we could have passive KISAs based more on their moral alignment, but I'm focusing on the more romantic knight version here). Perhaps this evens out once a relationship is started, and of course this is the same regardless of straight or queer relationships, but maybe this is why the KISA archetype is rare even in a straight context and practically non-existent in a queer one.
The second is again, kind of standard for any player-controlled character. If KISA are also protective and stalwart friends/lovers, that is a role that most players would prefer to play themselves. Like someone else mentioned in a different thread, we don't usually see the PC as shy or timid, but instead as confident and assertive in all aspects. Maybe writers are worried that most PCs want to be the ones "sweeping their love interests off their feet" instead of being the ones who are swept? Even Cassandra is said to be a secret romantic, and so maybe she'll subvert the KISA relationship anyway in this regard. A male KISA love interest towards a female PC usually wavers between acceptance of being less awesome than the female PC and explicit shows of protectiveness (ex. Alistair in DAO). It's hard to say if the female KISA love interest falls under the same behaviours, but I would assume it would be yes as well. In a gay/lesbian/queer relationship, maybe writers are concerned about who to attribute certain behaviours to without potentially offending their audience--would a male PC be offended if a male KISA talks about wanting to protect him? Would a female PC be offended at being coddled and shielded by a female KISA? The potential controversy might deter writers from attempting these kinds of characters.
And lastly, linking back to the first example, maybe the still-present homophobia/aversion to homosexual content is also making writers wary of creating queer KISA characters who flirt or approach the PC. Most obvious example would be the gay Anders debacle in DA2. When I played a lesbian Hawke I just sighed and rolled my eyes at Anders's flirting, accepting that and never really thinking more about it until I heard about the heated reactions from some fans who played male Hawkes.
Apologies for the meandering argument, it was hard to keep it focused on queer KISA relationships, since the tropes apply to straight relationships too, and even harder to find female examples
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