Inspired by this post by whovianconfessions on tumblr:
In The Doctor's Daughter episode, I honestly think that Jenny looked like Rose a tiny bit. I think that's why the Doctor was so hostile to her at first. Because that's what his and Rose's child would have looked like if he hadn't lost Rose.
Author's Note:
It's probably been done before but this is my take on the Doctor's feelings towards his daughter. It's been a while since I've seen this episode so I apologise if anything is in a different order from what was shown.
"Hello, Dad!"
The first words she spoke kept on ringing in his ears. For years, he had tried to block out the painful memories of his time on Gallifrey with his family and now the memories had come flooding back. All because a girl, a genetic anomaly, had called him 'dad.' But, there was something else about her…
The Doctor was distracted from his thoughts. Donna had decided that the girl (although technically true, he still couldn't think of her as his daughter) needed a name. The Doctor agreed silently but was a little taken aback when Jenny was chosen as he thought a different, more flowery, name would suit her better. The Doctor abandoned that thought as it became apparent they needed to run.
o.o.o.o
Later, the Doctor, Donna and Jenny found themselves in a prison cell.
"He saves planets, rescues civilisations, defeats terrible creatures and runs a lot. Seriously, there's an outrageous amount of running involved." Donna was telling Jenny about the Doctor while simultaneously trying to get him engaged in the conversation.
The Doctor stood brooding against the wall. What was it about Jenny that infuriated him so much? Although he hated guns, he didn't really mind that Jenny was carrying a gun because she was conditioned to fight, having been born in war. So, it wasn't that. He should be happy that he had a family once again. Perhaps he was scared of getting too attached in case she was taken away from him. Yes, that was why I'm distancing myself from her, the Doctor thought. But there was still something niggling away at him. A flash of yellow in the corner of his eye caught his attention.
Her hair. It's blonde just like… After all this time, it was still painful for the Doctor to even think of Rose. He cursed silently. The universe was playing a cruel trick on him, creating his daughter to look exactly like Rose. No, not exactly alike, more like 50% Rose. He gulped as he thought of the implications.
When Donna tried to get his attention, he was still wrapped up in his thoughts that he blurted out something about Jenny not being like him. He instantly regretted saying that. In an attempt to make the Doctor see what was in front of him, Donna asked for his stethoscope to check something about Jenny. Donna passed back the stethoscope so he could listen. His face lit up as he heard the double heartbeat. That was the moment the Doctor recognised that Jenny really was his daughter and it felt like a weight had been lifted.
"Right," he said. "Let's see about getting out of here."
o.o.o.o
Jenny lay dying in his arms. She had stepped in front of the gun in order to save the Doctor. Please, please regenerate, he silently begged. He couldn't help but think of the last time he had said that, on the Valiant, but this time was different. It hurt so much; a raw pain. It was like losing Rose all over again. His eyes raked over Jenny's prone form and even now, he could see the resemblance between the two. A few hours ago, he shrank away from the possibility and responsibility of being a father. But now, he had finally accepted it. He whispered over and over that he was sorry. He wanted to tell her how he felt. The Doctor lost all track of time as he cradled Jenny in his arms.
"Jenny, I..." He began to say.
But it was too late, the life in Jenny had vanished. He felt himself being gently pulled away and enveloped in someone's arms. That hug told him all he needed to know; Jenny would not regenerate. He let out a sob as he wished over and over that Jenny was still alive. The Doctor would take her in his Tardis, he was sure Donna wouldn't mind, and they'd travel the universe.
As they laid Jenny to rest on a bed of flowers, the Doctor was still thinking of the places he would haven taken her. First and foremost in his mind was the planet Barcelona. Even though he said he would, he hadn't been there with Rose so it would have been fitting to go with Jenny, his daughter that was so similar to Rose. Suddenly, grief overtook him and he began sobbing again.
"Rose," he mumbled.
Donna gave him a curious look as she wrapped her arms around the Doctor. She soothed him, "Come on, I think it's time we went back to the Tardis. You might want to be alone but know that I'm here with you if you want to talk or anything."
The Doctor nodded slowly and allowed himself to be led away. He stopped and bent down. When he straightened up, he held a red rose in his hand which he placed next to Jenny. It was his way of saying goodbye to the girl who had been in his life for only a few hours but would remain in his hearts forever.