You begin to think you're invincible after a while. Travelling with the Doctor will do that to you. After jumping out of that magic blue box, chasing after aliens, werewolves, vampires, and anything else you can never imagine, how can anything get you?

Because with the Doctor by your side, you know that all he has to do is grab your hand, and whisper, "Run". And you do. You run until your legs ache, until your feet are bruised and blistered, until your heart is pounding out of your chest, until your eyes are streaming from the wind whipping across your face.

And then you burst through the doors of the TARDIS, your hands connecting with the old, new, and so very blue wood, and as the doors close behind you, and her telepathic field envelopes you, the adrenaline pumping through your veins forces a laugh from the pit of your stomach.

You've survived. Again.

And he's dancing around the console, talking at a hundred miles an hour, pressing buttons and pulling levers, and you know that you're home. Right here, right now, this is exactly where you're supposed to be.

Sometimes you don't laugh. Sometimes the blood that is strewn on the fields of battle that you have left behind is too much for you to bear, and instead of a laugh, you have to cry. And then he hugs you, holding you tight to his chest. He may, more often than not, seem like a child on caffeine, and he may dance like a drunk giraffe, but when you need him, he's always there. He's strong, and he's solid, and he will protect you with everything he's got. Because he knows what it's like to carry that burden, and he cannot stand the fact that some of that burden is now yours to shoulder. So he does his best to hold you up when your legs are seconds away from betraying you.

With him, you will always survive.

And then you go home. He flies of to some faraway planet, thousands of years in the future, and, suddenly, you're on your own. When the nightmares hit at night, and your legs give out, there's only the floor to stop you falling, and falling, and falling.

But that feeling of invincibility is still there. You still believe, in your heart of hearts, that he will always be there to grab your hand, and whisper, "Run".

But he can't always be there. And I realised that just a little bit too late. When the floor caught me one last time, from a fifteen storey fall, I then knew that the Doctor may be able to save you from Slitheen, Daleks, Cybermen, and even the Master himself, he can't save you from your own thoughts that destroy you from the inside. There's no distress signal for that. You are on your own.

So as my eyes closed, and my last breath escaped from my lungs out of my tired lips, I finally accepted once and for all, that I am not invincible.

But, then again, neither is he.

A/N: Well, that got away from me a little bit – that wasn't the ending I had in mind! Please review!