An interesting little thing I thought of after watching the end of season 4 again (and crying my eyes out).
Disclaimer: I do not own Doctor Who. I do, however, seem to own the ability to make people cry.
"Doctor!" Rose rushed into the room in her flannel pajamas, quickly crossing empty space and sitting on the edge of his bed. The meta-crisis Doctor was dreaming. Or rather, she thought, having a nightmare. She gently shook his shoulders.
His eyes shot open and he bolted to a sitting position. He was breathing heavily, eyes unfocused. He suddenly turned his head, finally noticing the blond woman next to him. "Doctor?"
He exhaled loudly, pulling his knees up to his chest. The blanket offered little resistance and curled around his thin, human form. He didn't speak a word.
"Um, John?" Rose ventured softly. It had been two months since the real Doctor and Donna had left them on Bad Wolf Bay. He had insisted on being called John Smith from then on, something that she still wasn't used to. Pete's house was large enough for them to live there in luxury, John Smith included. He always seemed to wander, though. Wander through the garden, through the shops, through... Anywhere that wasn't standing still.
He finally raised his head and she saw tears on his face. They were pouring from his dark eyes. "It wasn't... Well, maybe it was." Even his mannerisms were the same. Well, most of them.
"Was what?" Rose watched him with concern, turning on the desk lamp he always used to read books. She wasn't used to the fact that he was not her Doctor.
"I had a... dream. A dream about Donna." He made no move to wipe the tears from his face. The light from the lamp made them shine. "She was..."
"What?" Rose prompted, hesitantly laying her hand on his back in comfort. "Did she... die?"
"Not physically," he said, staring at the wall across the room. It was white; the absence of color. He hated it.
"Then...?" She spoke quietly, encouraging him to tell her about it. When she was a small child, she always talked to her mum when she had a bad dream. It always made her feel much better. "I'm here, you can talk to me."
"She was brilliant," he replied softly, sniffling. The tears didn't stop. "She was so brilliant."
"I liked her," Rose offered. "I did, I really did. I didn't get to know her very long, but she was... She was like you." She found herself saying that, though she wasn't quite sure why.
"When the meta-crisis happened, Donna got my mind and I got her... well, her humanity. But I could see into her head, Rose." He finally turned his brown eyes on her, not quite as old as the true Doctor's eyes, but still crying. "She thought that she was worthless. No matter how many times I... He told her that she was brilliant, she never believed him. Not even for a second. I could see it in her head. She thought that she wasn't worth it." He fell silent, staring at the pattern on the blanket before continuing. "I have seen so many things, Rose. Things that even you wouldn't believe. I have seen so many people die, so many tragedies. But Donna..."
Rose was silent, just watching him.
"And it's my fault! I should have taken her somewhere safe before charging in like the reckless idiot I am." He buried his head in his knees. These emotions were human; they were Donna. That was all he had left of her.
Rose gently rubbed his back, not sure what to say. "Hey now, it wasn't your fault," she said encouragingly.
"But it was," he said angrily, lifting his head. "The Donna-that-was is dead now."
"Dead?" she asked, confused.
"There has never been a human-Time Lord meta-crisis because there can't be," he explained, eyes shining with tears. "He would have wiped her memory. Otherwise, her mind would burn and she would die." Rose stayed silent. "It's my fault. After she changed, after... She realized just how wonderful she really was. She saw herself from my... From the Doctor's perspective."
"And the dream?" Rose asked softly.
Bringing him back to that thought caused a new wave of tears. "Her mother always told her that she was worthless. That's why she believed it. Because the person that should have loved her the most thought she wasn't worth it."
Rose was silent again. She didn't know much about Donna. It felt awkward, that there was nothing she could say to comfort him.
"It's my fault," he said again. "She's back to the way she was before. She thinks she's worthless again. She'll spend the rest of her life thinking that, knowing that her mother thinks her useless. In the dream, she was crying. I have a jumble of her memories, in my head. Things that I saw. Feelings that I felt. She wanted to die, back when she was young. She wanted to die because it was easier than dealing with the sadness, the overwhelming sense of worthlessness. And the worst part is, she thought that not killing herself was being cowardly!"
He slammed his hand down on the bed with a muffled thump. Barely audible or noticeable, just like him. Hollow. Empty. "She should have known that it takes courage to live another day. Look at me, I should know." He fell quiet. "I never told her that. And now I'll never get to. I killed who she became."
They were silent for a long time. An hour passed with no sleep, just silent tears. Rose eventually stood from his side, going back to bed at his insistence. The "Doctor" continued to cry quietly until dawn, hating himself and mourning the loss of his greatest friend and the amazing person that she would never be.