It really does boil down to Tav’s facial expressions. Which look particularly weird because they also always enthusiastically participate during the actual kiss. It’s the before and after that feel way off.
The line between abuse and kink is consent. Given that Tav agrees to become his spawn, can leave him at any time before the epilogue, and is asking to be kissed, I’d like to think Larian was trying to show a domination kink and got some details wrong.
Although it does feel like at least one writer can’t wrap their head around why someone might be cool with being the submissive partner. Especially when we have options like “Come on, let it hurt.”