Why is the ML lettinf the MC stay with the abuser? Like you see the bruises on his body an...

if I understood correctly...ML is a visitor from another country (an illegitimate heir).
MC is being punished by the king of Kallak (his uncle?), for allegedly killing his brother (aka MC's father).
Instead of death, MC got imprisonment as a slave. So yeah... unless he wants to start a war, it'd be difficult.

That makes sense, thanks