Sun’ra is a switch. In his base mentality, or when he is super comfortable with someone, he will bend to whatever they are most comfortable with. If they need someone to be more domineering, he will fulfill that roll for them, or if they need someone more submissive, he will be that for them instead…
With a Matriarch or Matron type Keeper(or any female Keeper) woman, he will automatically take a submissive role unless they desire demand otherwise from him. With males, he will automatically fall into a more dominant position, and if they resist, attempt to break or otherwise force them into submission for his desires.