My twin sister and I became closer than ever (PART 16)

I'm M20 and she's F20, reminder: We kept our conversation going about the morality of sex as twin siblings

I'm not kidding, we actually sat there on her bed and debated as if it was a presidential debate on this matter. Her stance was that sex as twins isn't even "incest" since both parties consent, and it's not those freak shows with old parents attracted to their young kids. My stance was that even though I am sexually attracted to her, we remain siblings who grew up every day together, who took baths as babies together, who went to the same school and everything, and our religious obligation would highly put us into hell at some point.

Part of me really really wanted to do my first sexual time with her, but I just couldn't face it morally speaking, and I told her "no matter what you think, we are not gonna have sex". She laughed as ironically enough, I was just rubbing my dick inside her ass a while ago, but she agreed with a sigh, "Fine. Have fun having unexperienced sex with your cute girlfriend."

That's when the doorbell rang, it's been two hours we've been chatting. She quickly put some trousers on, and an actual shirt and told me to open the door that it's for her.
As expected, the newcomer was one of her friend, or more like "sex-friend". As I've stated previously, my sister has always been an engaging lesbian. She'd always call over girls and I'd back up for her to our parents, and she'd have sex in her room for a night or two with her door locked.

"Hi, is Sanaa ..." the new one said. Blonde, +++ skinny, shiny eyes, a nice pair of melons Billie Eilish-type (which is still not half of what my sister has), and a small ass. My twin quickly joined us and hugged her "friend", she said, "that's my dumbass of a brother I told you about. He won't bother us, he knows what's up". The girls got into the kitchen, then minutes later in my sister's bedroom. I already imagined them naked kissing, and this only time, her room door ... wasn't locked

(Part 17 later)