The boyfriend's Ex. A mystical creature of which we typically only hear stories. You know the ones, similar to the ancient legends of the Minotaur - human body, head of a bull, teeth of a lion. The exaggerated enigma, always more of an asshole or a perfect dream. It's the unknown of this creation that enraptures. And the opportunity to learn about them is an allure that very few can pass up.
Extraordinarily I have little desire to learn more than I already know about the 20% Russian's Ex. I know she is in another relationship, I know she calls when she's drunk (even though her friends tell her not to), I know she was hurt when he said he was bringing me home to meet the family, I know she got over it and apologized. I know she thought she and the Russian would end up together (very sweetly ruled out by him). But do these little nuggets of knowledge really add up to much? It sounds eerily like 'I can't/won't have you anymore but no one else should either' syndrome. Frankly an all too common post break up affliction.
Should defend my position? Force him to cut off all communication and set her up as an adversary? Some think that even once you’re the leading lady you still need to fight and to defend your position military style - 'Just because you're in Baghdad doesn't mean the war is over'. But simply, I don't live in fear of her enough to do that. Life is tough enough without trying to fight the ghosts of the past.
On the other hand, I do take potentially sick enjoyment out of being the Ex and in effect, interviewing next round applicants. My childhood sweetheart brought me a girl once who was virtually peeing her pants with nerves. To her, I was more fearsome than his mother (quite a feat). But I digress, ultimately, as much as you like or dislike the new replacement or as much as your predecessor likes or dislikes you, we can't exactly go about life living as though the existence of someone else is a personal insult. It's just not practical.