If you take Gin and Sherry with their character back to when they are still in organization, this is what comes to mind:
*Gin goes to the lab where Sherry is to kill some time*
"Hi, my bad little kitty~"
*Sherry ignores Gin*
"Ne, Sherry, let's have some fun, shall we?"
"Go away, I'm busy."
"Come on, don't be so cold~"
*peeping from a slightly open was a jealous Vermouth*
"I told you I'm busy!"
*Gin gets a bit irritated, holds the tip of Sherry's chin and forced her to face him* "Don't get too cocky, you bitch. Just because I'm being nice to you here doesn't mean you can act all high and mighty. I told you let's HAVE SOME FUN!"
"I'm not interested in a goat like you."
"Hmmm... I see, so that's how it's going to be. Well, you see... about your sister... she left some of her trails from the previous task she was assigned to, if I hadn't butt in and cleaned up her mess she left behind... that person would surely ordered her to be eliminated. The only reason I helped that woman's ass was because of you... If you make me hate me now... I'd definitely-"
"I understand. I'll do as whatever you say... but please... promise that you won't harm my sister!"
*Gin smirks* "You said you'll do whatever I tell you? Good... then... let's ** ** *****."
Using her sister as hostage to sexually harras Haibara, I think that'd work, too... probably.