Leave it as a one time thing for now. I doubt people who saw each other as brother and sister would be so okay with that kind of relationship so soon. Maybe if you get him drunk tonight they'll be together. Haha.
I don't think I'll be able to do the all night to be honest. Sorry!! >.< I have a headache coming on and I'm still feeling pretty rotten with the chest infection. I promise I'll reply as soon as I wake up though. Sorry again. G'night!!