So. This just sort of came to me while I was watching the Lazarus Experiment and I had to write it. Doctor Who is stirring up my muse again, it seems.
A Rose by Any Other Name
She was so much like Rose that it hurt sometimes. She would say something, or do something, and it was all he could do to keep himself together. When he'd first started his travels with Martha, he'd told himself it was just because he owed her. One trip in the TARDIS and he'd drop her off back home, so he could jaunt off across the universe alone as he'd originally intended.
But that one trip spiraled out of control into something bigger than he had realized. Martha was so smart, and the way she looked at him made his hearts twist in his chest because it was how Rose had used to look at him. All shining eyes and hope and faith. It wasn't fair to Rose or to Martha, because he'd told himself he'd end it with Rose, and here he was stringing along with a girl just because she reminded him of his pink and yellow princess.
And the worst part was that he knew they'd both forgive him this weakness if they knew about it. They were both so wonderfully forgiving and loving and he didn't deserve it. Maybe, once upon a time, he might have deserved Rose, might have been good enough for her, but not anymore. Losing her had broken something in him, and he didn't know how to fix it, not even with all his genius and his sonic screwdriver put together. And he certainly didn't deserve Martha, not when he only kept her around simply because he couldn't bear to be alone.
He'd never be able to give her what she wanted because he'd already given that part of himself away. Physically, his hearts were still there, still with him, but he had to check almost daily to ensure himself that they hadn't been ripped out and sealed beyond the void with Rose. Martha and Rose, Rose and Martha. Sometimes it hurt so much that he could hardly stand to be in her presence. Her sameness and her differences mocked him alike.
Every word, every expression, every touch between them was an agonizing reminder of Rose and the fact that Martha wasn't her. Countless times he'd looked at Martha and seen Rose instead. Her name balanced on the edge of his tongue, waiting to fall from his lips in grief, in agony, but somehow he always held it back, managed to morph the sound until it broke apart into two syllables and fell from his lips cold and distant. Martha.
And he knew, he knew, that he'd have traded one for the other in the space between his heartbeats. A rose by any other name would smell as sweet, but he didn't even have that. All he could lay claim to was a cheap resemblance: a carnation hiding in the guise of a rose.
It was hardly a surprise when she left. He watched her go with only the remorse of knowing he'd done her wrong. A carnation can never be a rose no matter how it tries to change it's scent. And he had fallen for the rose.