Disclaimer: I do not own Doctor Who. All rights belong to the BBC.

A/N: Cold Blood was amazing. I knew that something was going to happen to Rory, but I could never have guessed the true aftermath after his death. The scene between Amy and the Doctor afterwards made me cry. But it also made me think; I wondered what had happened after the Doctor and Amy returned to the TARDIS, so this one-shot was created.

Guilt. An emotion that the Doctor was all too familiar with. He'd been responsible for so many tragedies, so much hurt, that he often found himself drowning in remorse.

But after he'd regenerated into his eleventh form, he'd promised himself that this time he'd be different. He was going to go back for little Amelia Pond, and keep her safe until she blossomed into a young woman.

That was his first mistake. When he returned, little Amelia was a 19 year old, feisty kiss-o-gram, and he didn't blame her for knocking him unconscious with a cricket bat after he'd kept her waiting for so long.

To make amends, he intended to go back for her, just after he ran his new TARDIS in, of course.

That was his second mistake. Five minutes turned into two years, and Amy was still left waiting. After she'd accepted his request to travel with him, he thought that he'd finally be able to heal all of the pain that he had caused her.

He almost did achieve that. They'd had so much fun travelling together, despite nearly losing her to the weeping angels. He'd been so relieved when River Song had teleported her to safety, believing that he hadn't failed her after all.

And then she told him about her fiancée, Rory.

The Doctor didn't have anything against Rory, not really. He'd been disappointed at Rory's lack of reaction at the size of his TARDIS, and maybe he was slightly jealous of the relationship he had with his Amy, but he genuinely liked him. He liked his clumsiness, he liked his goofiness, and he was hilarious to travel with.

Having Rory onboard meant that Amy had no reason to return to Leadworth. And that thrilled the Doctor, believing that they were going to spend the rest of their lives with him.

But when a trip to Rio turned into a trip to the Silurian city, everything that the Doctor had hoped for was destroyed.

Seeing Amy's grief at losing her fiancée killed him too, especially because it had been his entire fault. If he hadn't been so damn curious about the crack in time, they would have been safely inside of the TARDIS before Restac could reach them and shoot Rory, a laser that had been intended for the Doctor.

What made it worse was that as much as the Doctor had tried, he couldn't get Amy to remember Rory. It looked like she would have, but when the TARDIS jolted them to the floor, she forgot all about him, too stunned as she fell to the floor.

The Doctor knew he should have been stronger; he should have been able to keep Amy from forgetting the man she loved. But he had been weak in the presence of her vulnerability, and she'd forgotten all about Rory.

Rory only existed in the Doctor's memories now.

Every time the Doctor looked at Amy's carefree, smiling face, both of his hearts panged with regret, knowing what she had truly lost. And it was his fault. Entirely his fault.

Amy would never know the burden he carried. She would never be able to understand what she'd lost, because for her, Rory had never existed.

The Doctor had failed her. Again.

"Penny for your thoughts?" The cheerful voice of his companion asked, breaking the Doctor out of his train of thought. "A problem shared is a problem solved."

Not this time.

The Doctor offered Amy a small smile, not having the energy to muster up a grin. "I'm only thinking about equations, nothing very interesting."

Amy seemed to buy the lie. "Wow, is that what you think about in your free time?"

The Doctor's thin smile wavered. "Yes, that's all I think about." He answered, his voice sounding sad, even to him. "Now, I think it's time we get some sleep before our next adventure, don't you?"

Without giving Amy a chance to reply, the Doctor dashed up the console room stairs towards his bedroom, suddenly desperate to be away from her so he could let his façade slip away.

Once he reached his bedroom, he threw open the door and stumbled into the room, gasping as he began to feel the guilt choking at him.

He staggered towards his bed, grasping in his pocket for Amy's engagement ring. He didn't understand why it hadn't disappeared too, but he couldn't find the energy to figure out why it hadn't right now.

His fingers closed around the box as he sank down onto his bed, and he pulled it out of his pocket. With shaking fingers, he prised the lid open, feeling tears well up in his eyes at the sight of the simple, yet elegant diamond ring.

He could never give this to Amy, for she never knew the person who bought this for her. And that crushed the Doctor.

She had been so close to marrying Rory, but the Doctor had interfered without meaning to, whisking her away on the night before her wedding. So much for compensating for his mistakes. He'd just ruined her chance at a happy-ever-after instead.

He knew that he should take Amy home, but how could he, knowing she had nothing in Leadworth now. He couldn't leave her alone again.

But he couldn't keep her with him either, for every time he looked at her, he was reminded of what she'd lost.

The tears he'd managed to withhold streaked down his face, and he closed the ring box, returning it to his pocket.

"Doctor?"

He turned his gaze towards his bedroom door at Amy's concerned voice, remembering that he'd forgotten to close his door behind him.

Amy stepped into his bedroom, and when she saw his tear-stained face, she hurried over to him.

She sat down onto the bed beside him, and wrapped her arms around his shaking form.

The Doctor froze for a moment, realising the irony of the situation. He should be comforting her, not the other way around.

But reality was cruel, and he was in fact, the victim of this situation. He slid his arms tightly around her waist and pressed his face against her neck, allowing his tears to fall freely.

Amy rocked his sobbing body gently, murmuring, "Whatever's happened Doctor, we're going to get through this."

Her reassuring words were meaningless to him. There was no way he could forgive himself for what he'd done to his Amy, to Rory, to Donna, to Rose…to all of the people he'd befriended and loved.

He was a monster. It didn't matter how many lives he'd saved, because he ended up losing everyone he ever grew close to.

And that hurt. It really, really hurt.

Please let me know what you think of my one-shot :)

Hayley x