Wow, perfect, I'm sitting here thinking, damn I wish I wrote that :D
I especially enjoyed the motorbike ride, saving lily, the whole interaction between the four of them, and omg, the sex was blistering.

And then sirius - "No, see, it wasn't," Sirius says suddenly. Remus looks up from the paper, politely puzzled.

"I'm sorry?"

"It wasn't just sex. I've had loads of just sex, and that wasn't it, Moony."

I'm bookmarking this *am completely in love with it*