idea I hope to one day make into a game/comic
>(You) the big brother character
>Have a sister (They're a futa)
>You guys actually get along really well and like each other, though she has become a hikimori and won't leave the house without (You).
>Futas are an uncommon thing in this world but aren't considered strange
>Most futas are the stereotypical super high sexual needs/urges types, your sister included though she tries to hide it from you.
>To help your sister you deal with her urges you decide to go out and find girls either by tricking them into thinking they're going to date you only to then hand them over to your sister to be her "onaholes" or have them know from the start.
I know it's basically the getting cucked by your futa sister storyline, but I always kinda felt like a weird satisfaction in the idea of if I had a futa sister helping her get girls to fuck and that it was an "inside job" all along, I never had any intentions of dating the girl that sister "stole" from me and futa sister was in the know as well with only the girlfriend not knowing brother and futa sister were accomplices all along.
also futa sis is a brocon but hides it and wants to get fucked/impregnated by (You)