I'd say "us after dark," but we're like this in the day too

but she knows that when we’re alone. she has me absolutely wrapped around her finger. that i’ll do anything to make sure my darling little sister feels happy. i would drop to my knees just to make sure she can feel relaxed. kissing her all over so she knows how loved she is. slowly and gently fucking her so she can unwind from her difficult day out of my arms. holding her after and petting her hair and giving her soft gentle kisses as we just enjoy being in the others arms.

Big sister using you to indulge all her own fucked-up kinks. Big sister noting your preferences but instead of respecting them she reshapes them to better suit her. Big sister training and conditioning you to be her perfect sub. Big sister teaching you to always come to her for comfort even when she's the one abusing you. Big sister intentionally getting you to trauma-bond with her.

Big sister taking photos and videos to use as even more blackmail material. Big sister deciding they're too good not to share and posting them online under a pseudonym. Big sister selling porn of you to make some extra money. Big sister taking control of your finances and wardrobe and diet and every other aspect of your life.

Big sister... forcing you to develop healthier habits and not letting you hurt yourself. Big sister making you break up with your jerk boyfriend and quit your shitty job to be her full-time personal pornstar. Big sister covering for you if anyone else gets close to discovering your secret. Big sister insisting it's just because she wants to keep her leverage but there's something softer about the way she holds you.

Big sister working hard to provide for both of you between her normal job and managing your porn career. Big sister making you do all the housework but it kinda feels like you're just doing your part to support each other. Big sister showing you how popular you are online and immediately blocking anyone who's rude or creepy. Big sister trusting you to interact with other people again so long as you don't let the secret slip. Big sister getting so fiercely protective against anyone who might mistreat you.

Big sister showering you in praise and affection when you do a good job servicing her. Big sister feeling some remorse for forcing you into all this and you end up comforting her. Big sister moving with you away from anyone who knows you're sisters and introducing you as her girlfriend so she can be more openly affectionate with you. Big sister taking you on romantic dates, allegedly just to make the girlfriend story more convincing but you both enjoy yourselves.

Big sister still acting like she holds absolute power over you even though telling people you're a siscon doesn't really make as effective a threat when she's just as guilty as you are. Big sister having such joy in her voice whenever she says you're hers.