Prologue
There was a reason why there were no female Death Eaters other than Bellatrix. And that reason was a snake by the name of Nagini. This rather possessive reptile did not want any "competition" with her "master"—referred to and feared of as the Dark Lord, Voldemort.
And contrary to popular belief the real "master" of the relationship was not Voldemort, but his "pet" snake. Why do you think she was always curled up around his neck and other body parts? It wasn't to "snuggle up"; it was so she could strangle him if he ever managed to displease her.
Now, I'm sure you're asking, if she didn't want any "competition" how come Bellatrix is a Death Eater? That, my friends, is the tale I am about to tell…
A/N: I am still comtemplating the rating for this, but as there will be sex between all three of them though NOT a threesome.... or maybe there will.. I'm still deciding) it will probably be M just to be sure. But it will probably not be very graphic since I'm not really corrupted enough to describe sex between Nagini and Bellatrix (how would that work??) that well. I don't watch snake porn! (not in public anyway XD)