It's a good thing I'm romancing her in my Astarion origin playthrough then. Otherwise the ending might be me and Karlach both on fire on the opposite ends of the pier while Shadowheart's drowning and the rest of them just watch.
I've never played as origin character (other than Dark Urge) so I do wonder how that'll end up, because I know one of her ending has suggestions that may not be entirely compatible with Astarion's condition. I know playing as origin companion gives you their own unique ending cutscene, and it may overwrite that of the romance, too. Others who have experienced it would have to confirm/deny that.
