@papercut_ninja For me, I honestly think it's just not very developed at all. I think it's cool if characters don't have their sexuality or identity be front and center, and don't think it's needed for it to be constantly remarked, but it does frustrate me a bit that a "lazier" playersexual mechanic is rewarded by awards when it could've been more meaningful and easily included to make her canonically pan. Like they did with Astarion except for all the online discourse about whether it "counts" because of his circumstances.
I think her being in a romantic relationship with Nocturne is partly HC territory (people have theorised pre-transition Nocturne was her Dream Visitor in EA, though, but it's just a theory... a game theory) and I also don't think that line about Karlach is enough to confirm she's bisexual, unfortunately. Would've been nice if they've pushed the tension with Shadowheart and Lae'zel a bit more, I suppose, since the devs joke about it a lot now.
I don't say this with ill intent and I hope that's clear, I'm bisexual myself and I like seeing bisexual characters on screen. Unfortunately I don't know if that's what I'd consider Shadowheart, although it's easy for me to HC her as such.