As generic as possible. The MC is a stand-in for the player so you don't want to do anything stupid like make him a tatted-up wanna-be edge-lord. That's why Mario has no personality and we never see Master Chief's face, so that everyone can imprint themselves on him.
Like in all (straight)...
In order:
Wincest- Specifically Mommy and Big Sis with impregnation
Lols- Willing, of course
Assertive Female- Not domination, just girls wanting it
Beasty- Girls enjoying themselves with willing dogs/horses
Vore- Girls willingly being devoured by snakes/beasts (non-fatal) (my weird fetish)...