Author's Note: This is just a tiny fic that popped into my head earlier today, hope you enjoy.
This isn't meant to take place directly after 6.07. I meant it to be a while after, because I don't think that Amy would be able to understand and accept that River turned out pretty awesome regardless so soon after losing baby Melody. Just my own opinion.
"But Doctor, where is Melody?" Amy asked yet again.
She was in protective mother mode, and didn't want to listen to any more of the Doctor's roundabout explanations. Surprisingly, the Doctor said nothing for the moment, just walked around the TARDIS console to stand next to River. He gave her an unreadable look. River looked like she was about to say something, then decided against it, closed her mouth again, and looked down at the console. Then the Doctor turned to Amy and Rory with one of his over-the-moon, delighted smiles.
"Mr. and Mrs. Pond, I'd like you to meet Melody Pond," he said dramatically, sweeping an arm toward River.
"Doctor," Amy replied, torn between confusion and frustration. "That's River."
"I know that's River," he said. "That's Melody."
"Doctor..." Amy trailed off as understanding hit. "That is not possible. That is..."
Amy and River just stared at each other for several minutes, and then suddenly they were in each other's arms, laughing and crying simultaneously. Rory, oddly, was staring at the Doctor silently. Finally, he spoke.
"My daughter." The words were little more than a whisper.
"Yes," the Doctor confirmed, grinning.
"My daughter," Rory said again, this time in a somewhat louder, and angrier voice.
The Doctor, still grinning like Father Christmas, simply said gleefully, "I know!"
"My daughter, Doctor!" Rory yelled, and the smile seemed to slide right off the Doctor's face as he followed Rory's train of thought.
"First, you kiss Amy-"
"Well, technically, she kissed me-"
"And then you... you... my daughter, Doctor!"
"Well, I can explain that, you see, I didn't know before... and I know now, and I suppose I will later when she's... and she won't know me... and I..."
The Doctor had begun to back away from Rory as soon as he started shouting, seeming to be afraid of another punch from his gun arm, and now was leaning backwards off the railing. Rory had followed, and now stood almost nose to nose with him. Amy and River, still arm in arm, watched the boys with bemused expressions, and then decided to interrupt the Doctor's botched explanation in order to salvage the situation.
"Oh shut up Rory," Amy said, smiling, "She's a grown woman. And a pretty badass one at that. And, Doctor, well, you don't want to know what I'll do to you if you let anything happen to her."
Rory's face returned to a more normal color, and he gave River a hug before putting an arm around his wife.
"I told you," Amy whispered in his ear.
Rory looked down into her face, puzzled. "Told me what?"
"That she'd be a superhero."