"I'll see you there," River said.
"I look forward to it," the Doctor said.
"I remember it well," River said.
The Doctor chuckled and walked away.
"Doctor," River called.
The Doctor stopped.
"You never could ask for anything, could you," she said.
He turned to face her, giving her his best clueless face, hoping she was going to mention flying lessons.
"I promised you flying lessons."
The Doctor walked toward her, still pretending to be ambivalent. "But you've got handcuffs."
"Do I need my hands to teach? Fly. Straight up. Show me you can fly straight up thirty feet."
"I can do it by myself, I just can't carry someone with me!" the Doctor argued. He jumped into the air and flapped his arms.
"No! No!"
He floated back down, surprised.
"Don't jump, and don't flap your arms like a frolicking little girl."
He stuck out his jaw at her. He closed his eyes and concentrated. He relaxed and breathed deeply. He opened his eyes and he was already a foot off the ground. He floated gently upward. Amy gazed at him in surprise.
He felt like he hit his head on the ceiling. His feet were about six feet off the ground and he couldn't fly any higher.
"Don't stop, keep going," River said.
"I can't," the Doctor growled.
"And why not?"
"This is the highest I can go when I don't flap my arms! Sometimes I can get a little higher, and sometimes I can't even get this high. I always run into something. It's like there's this barrier. I know there's nothing there, but I can feel it stopping me."
"Do you know where that barrier is?"
"What do you mean?"
"It's not in the air above your head. It's inside your head. There's a barrier in your mind, telling you that you can't go any higher. Break down the barrier in your mind, then it will be easy to break the barrier above your head." As she spoke, her feet rose off the ground. Even with handcuffs, she floated higher and higher into the air.
The Doctor stared at her with jealousy as she rose faster and higher than him. He tried to fly higher. He only rose about an inch before running into the barrier.
"That's good, Doctor! A little higher is good, even if it's just one inch."
Her handcuffs beeped. "Oh! I think that's my ride," she said.
The Doctor flapped his arms to break through the barrier and flew up to her. "Can I trust you, River Song?"
"If you like, but where's the fun in that?" She laughed and teleported away.
The Doctor looked out at the ocean and floated to the ground.