Shirou refuses to leave

Shirou: you wouldn't dare do it in front of me

Aiden: oh really

Aiden: Sakura, get on your knees and take my cock out

Sakura: w-wait we're actually doing it in front of him, I thought you were making an idle threat

Sakura: I don't know if I can do this

Aiden: yes you can Sakura, and you will do it if you want to stay my girlfriend

Shirou: let her go it's clearly she doesn't want this

Aiden: shut your fucking mouth faggot

you then start kissing Sakura very passionately

and after kissing her for about 5 minutes you let go

Sakura then looks at Shirou

Sakura: sorry Shirou, you're a fantastic guy but I need to do this

Shirou: what, you're actually doing this

Sakura squats down

Aiden: go on take it out Sakura

Sakura unbuckles your pants and your hard cock jumps out against her face

Sakura: wow, I'm still surprised by the size

Shirou: holy fuck

Shirou was unable to see the size of your dick proper in the basement since it was pretty dark but now he can clearly see how much bigger you are than him

Aiden: go on start sucking

Sakura: just like last time

Aiden: yeah just like last time

sakura starts sucking your tip

Aiden: that's my girl

Shirou is speechless at what he sees the timid and quiet little sister of his girlfriend is sucking a giant cock in front of him

Shirou: it's not fair how can she be okay with giving blowjobs when Rin who is more sexually experienced has never sucked mine

Aiden: enjoying the show__

Shirou: O-OF COURSE I'M NOT

Aiden: then leave

Shirou: I'M STAYING JUST SO I KNOW YOU WON'T HURT HER

Aiden: as you wish, but I doubt she would mind

you see that Sakura's pupils have turned into hearts

Aiden: looks like she's completely in trance

Shirou: what are you talking about

Aiden: nothing, you wouldn't understand

Aiden: switch to your tits Sakura

Aiden: take off your bikini top and make me cum with your tits