It's just another day, just another fight on the Met steps. She thinks this might be it, that maybe this time she will turn her back on Serena, and no amount of heady laughter will be temptation enough to turn around again. And maybe Blair's chest already aches, and maybe she rubs her breast bone like something essential has been torn out, but in no way does that mean she'll forgive her.

Because Blair knows, deep down in the places she doesn't acknowledge let alone analyse, that her and Serena are not friends.

Oh, sure friends are given leeway to play dirty. The better the friend the dirtier the plays—everyone knows that.

Pictures of the latest Waldsen meltdown are splattered all over Gossip Girl's blog. Short skirts whipping around their legs, Blair's freezing smirk, Serena's heated gaze—it could be today, it could be a million days. This is what they do.

They are just pretty things. Shiny fragile porcelain. With slow burning anger, born of too many disappointments, Blair will destroy Serena over and over again. And Serena in pain hurts Blair in more ways than she can count, but she won't hesitate with the pretty shards of a broken blonde under the heel of her Manolo's.

And Serena moves with long, reckless limbs and no ability to slow down. She will break Blair with careless ease, splinter the brunette into millions of pain-filled pieces. And always after, Serena will cry pretty tears, and she'll be oh-so-very-sorry. But it won't stop her from doing it again and again.

This is not friends playing dirty. This is Serena and Blair, bound together in untold destruction.

They will destroy each other. The only people they will treat worse than each other is themselves.

Blair's eyes are open wide, and blind to most everything. She convinces herself that she is nothing like Serena. She is not passed out in hotel rooms with middle-aged soccer husbands. She does not stumble into her friend's penthouse at three a.m. with a trail of high-pitched laughter and tear-stained cheeks. She doesn't know the way alcohol poisoning will make you shiver and freeze in the dead of summer, the futility of being so desperately thirsty and not even able to hold down water.

No, no, she is far too civilised for that brand of self-harm.

And even if bulimia isn't the pale, sanitised thing those after school specials make it, well, it's still the most brilliant thing Blair has ever discovered. She feels immensely superior, when girls at school try to convince each other that they threw-up the half a chocolate bar they ate. As if it was that easy.

There is nothing easy about forcing yourself to eat half a fridge full of food, until your stomach aches and every bite invokes the type of nausea you shouldn't feel outside of an ICU. And still, even with abdominal muscles that know the drill, it's not simple to make a healthy body throw-up. It's hard, and it's messy, and you can't just brush your teeth after and forget it all. Because scrubbing stomach acid further into your teeth is a great way to qualify for dentures, and barely a minute goes by when Blair isn't thinking about her obsession.

But it makes her strong, it makes her queen, it makes her better.

They may be beautiful and loved, but I haven't digested a calorie in four days, is a thought that helps her last through four days of Serena-withdrawal.

And on the fifth day, Serena apologises.

Serena waits, hopeful and yet unexpectant, for Blair to return the words.

Instead, Blair thinks about shouting I don't even like you. It would almost be true, because it's easy to convince herself that she doesn't need Serena, at least when she thinks she's gone forever. She thinks of just turning around and walking away. But she just mumbles something inane, the desperation hidden deep, uneaten yoghurt in her hand. She's just pale porcelain on the Met steps, not wanting to be destroyed again, unable to choose anything else with a chest that aches from denying the most important piece of her soul.

Serena sits beside her, trampling over the rules of the queendom with her usual brashness. And Blair let's her, she bites her tongue when Serena steals a spoonful of her yoghurt and when Serena forces her to eat some of her own, she can't pretend that she isn't glad. Because there are all sorts of hurts that living calorie-free can't fix, and those are the ones that Serena soothes.

No, they are not friends. Friends implies that they could live without each other. Friends would be whole without each other. They are something else entirely. Something far more destructive. As it turns out, bulimia is only the second most brilliant thing Blair has ever discovered, the first cannot be described.