Lovely story! I loved the way that reality kept intruding on Percy's fantasies, like wondering if wall-sex would be uncomfortable, and all his little insecurities. (And it was very sweet that even in his fantasy, he was thoughtful of Tonks and used his arm to cushion her, lol!) And the whole thing about wondering what to call Tonks's, er, private parts was great, too! Like one of the commenters above said, one thing I hate about writing sex scenes is that the real words seem too clinical, and the various euphemisms are either too crude or too flowery for my tastes, so like Percy, I usually go the vague route! ;)
And yay, Percy got the girl at the end! I was afraid it was going to end on an angsty note, so I was very happy that they got together. ^_^