Hi! The fic you're looking for is called Death Eater Takes a Holiday by Leelee Potter.
Its a wonderful read, as I'm sure you'll know, and competantly written.
Here's the link to HP Fandom where its complete, it is also on ff.net but only up to chapter 67.
http://www.hpfandom.net/eff/viewstory.php?sid=564
Happy reading, enjoy!