The Doctor had promised to find Amy's baby, but he has a stop to make first.
He sets the TARDIS to home in on his cot, and his old girl takes him to his destination. When the Doctor opens the doors of the TARDIS, he finds himself in a nursery; the cot is there with the same writing River showed him at Demon's Run. A genealogic tree for a baby girl, with River's name as the mother, Amelia and Rory the grandparents, and his name – his real name – written as the baby's father. The ultimate spoiler, and yet River must have had a reason to show him.
The Doctor takes a moment to examine the nursery. It's painted with whimsical designs and bright colors. There's a rocking chair in the corner, a changing table, and a ridiculous number of toys. This place is warm and safe, and the Doctor is so very happy that River has obviously refused to raise a baby on the TARDIS.
The Doctor walks out of the nursery, trying his very best to be quiet just in case there is another version of himself lurking around. Best to try to avoid crossing his own time stream as much as possible.
He follows the sound of a River singing until he stands at the doorway to the back porch. He listens to her voice, so gentle and loving, and he wonders how she became this person after being raised by the Silence. The Doctor waits a moment longer, because he knows to whom River is singing, and that is still a terrifying thought. The lullaby is one that he hasn't heard in a millennium, a tune in a language that the Doctor didn't think that anyone else in the universe spoke before meeting River.
The singing stops, and the Doctor can hear the sound of a soft kiss. He doesn't know if he will ever be ready for the sight that waits for him.
"Hello sweetie," River says, and the Doctor can hear the smile in her voice. He opens the door and steps onto the porch.
"Hello," he whispers, his voice catching in his throat as he stares at the bundle in River's arms.
River turns to see the Doctor standing in the doorway, frozen with fear, but smiling so happily. She remembers this face from when she told the Doctor she was pregnant, from when he first held their daughter in his arms. "She doesn't bite," River says, as she nods to the seat besides her.
The Doctor's feet barely seem to cooperate as he stumbles towards River and the baby. He settles himself next to River, and her smile is the same warm, impossibly loving smile that he had seen at Demon's Run when she showed him their child's cot.
"When are you?" River asks, because it has never been more important not to change the future, not when their precious child is at stake.
"I've just come from Demon's Run."
River smiles solemnly and reaches out to take the Doctor's hand. "There's nothing you could have done."
The Doctor feels something break inside him. This woman will be his wife. The mother of his child. And he is the reason that she suffered for so long. "I'm so, so sorry. Can you ever forgive me?"
River smiles at him. "Always and completely."
The Doctor's eyes shift from River to the baby on her shoulder, swaddled in a warm yellow blanket to guard against the slight chill in the air. "Do you want to hold her?"
The Doctor swallows thickly, and all he can manage is a small nod. River extends the baby towards him. "Her name is Amy," she tells the Doctor, as he takes the child from River's hands.
"Hello Amy," the Doctor whispers. Tears fill his eyes. She is so incredibly beautiful. His daughter. "I'm your daddy."
Amy coos in his arms, and River smiles at the pair of them. "She knows who you are."
"So I help you raise her?" the Doctor asks, fearing that he had left River alone with their child as he traveled through the universe.
River laughs richly at that. "Do you really think that I'd let you get away with not changing half the nappies? You're home by 5 every day." River glances at her watch. "Which is soon, so you'll need to be going shortly." She smiles and can't resist the opportunity to say something that she hasn't in years. "Spoilers."
The Doctor holds the baby tighter to him. He doesn't want to let her go. "When is this?" he asks River.
"Sorry honey. You know I can't tell you that."
He tries to fit it into the timeline that he knows, tries to piece it all together, but it doesn't seem to work.
"You're clever Doctor, but you don't know everything," River says with a gleam in her eyes. "Just remember that Amy and I are in your future. Even when everything seems bleak, you just think of us." River cups the Doctor's cheek, and he understands from that touch that this woman has spent lifetimes comforting him. River leans forward to kiss the Doctor softly.
"I won't find her will I?" the Doctor asks, remembering that he left Demon's Run promising Amy and Rory that he would find their baby.
"It seems that you already have."
"But I won't save you. You were the girl in Florida." The Doctor's hearts clench at the thought of the little girl's terror.
"And I am the mother of your child. You can't have one without the other. So don't you dare go changing a thing. Not me. And not her."
"River-"
She shakes her head, not wanting to hear another apology. There is so much that the Doctor doesn't understand yet and so much that she can't tell him. She covers his hand with her own on Amy's back. "You need to leave my love," River tells the Doctor sadly. "You still have so much to enjoy before you get here. After all, we have to make her. You wouldn't want to miss that."
The Doctor laughs, though his eyes are wet with tears. He reluctantly hands Amy back to her mother. "We love you sweetie," River tells him. "And we will see you soon."
The Doctor is still searching for words when he sees a TARDIS appear in the yard. "Until next time Doctor Song," he says, ducking quickly back into the house so that his older self won't see him. The Doctor stays hidden behind the door long enough to watch his older self run up to River and Amy, a new stuffed bear in his hand for his daughter. He kisses River and their baby, looking happier than the Doctor can ever remember being.
Finally the Doctor pries himself away from the scene in front of him. Tears fall down his cheeks as he walks back to the TARDIS in the nursery. He knows now that he can't go in search of baby Melody, but he can go find his River. He can find her and tell her how much he will always love her. The TARDIS brings him to Stormcage a moment later, to a young River who loves him just as much as the woman he left with his baby moments ago.