"Amy, could you pick me up some Jammy-doggers, please? I'm all out," The Doctor asked his companion while he nervously fiddled with his bow tie.
"Why can't Rory do it?" She asked whining, not wanting to be the errant girl. The Doctor objected saying he didn't know the proper kind. With a roll of her eyes and a frustrated groan Amy walked out of the TARDIS door.
When she'd gone The Doctor began messing with buttons on the ships console, although Rory figured it was out of boredom, he wouldn't REALLY go somewhere without Amy like that... With those thoughts in mind it was a surprise when the TARDIS jostled and threw him and the Doctor backward and stopped with the screeching sound of the breaks.
The Doctor stood, looking I'll at ease as he fixed his bow tie once more, bracing himself for Rory's questions.
"Why'd we leave Amy?" was the first to leave his loyal lips. The Doctor cut him off with answers, the normal bounciness of his personality was not expressed in his sober tone, "If Amy were here it would ruin the point. I want to talk to you, Rory." He gestured to be followed as he stepped out of the door into some foreign market place and told Rory the when and where's of around them until he found a bench and sat, patting the seat next to him, inviting Rory. Nervous now of whatever the Doctor wanted to talk to only him about, he sat stiffly.
"I know you're worried about me and Amelia," the Doctor looked deep in Rory's eyes as he nodded sheepishly, somewhat embarrassed by where this conversation seemed to be headed.
"You don't need to be. I'm going to tell you a story. I was in love once too. Long before you or Amelia, or even this face. Centuries ago, although I remember her like yesterday, as do I remember the pain of losing her... Rose Tyler her name was was. The most beautiful and wonderful girl in all of time and space, but that's not the important part." The Doctor's face was a shadow of a memory, his eyes filled with a deeper despair than Rory had ever seen in his life combined. His expression grave and his gaze shifted, like he suddenly remembered the reason behind bringing up his pain once again.
"I lost her. My Rose wilted. She's happy, very happy. That much I do know, in a different world." The Doctor looked back at Rory, ready to make his final statement on the matter but read his companions intent curiosity and decided to give him what he wanted. He spoke more.
"I had to choose between being with her or saving two universes. Every part of me wanted to, and still wants to, rip apart both realities and be with her but I know I can't. She saved me, in my darkest time. Right after the Time War. Taught me love again and that I wasn't a monster. My Rose Tyler..." he started to trail off as he stared at a poster he was sure said "Bad Wolf" but figured it was nothing but an old memory come back. He continued to ramble in hopes of satisfying Rory's hungered looks.
"I hold a door open for her at the shop sometimes, smile on the street, but she hasn't the slightest idea of who I am. Not that it matters to me in the few seconds I get to see the smiles that lights up my world once more," he paused, "the point is Rory, Amelia is your Rose. And I'd never dream of taking another man's Rose." The Doctor finally made the point he brought Rory here to make.
"What did she look like?" Rory asked, insisting to hear more, "What happened to her? What was she like?"
The Doctor sighed, "She had blonde hair like the sun, sparkling eyes like the stars, a smile that..." The Doctor choked on his words, unable to speak as he looked in front of him.
"Like that. Exactly like that,"  he said unable to take his eyes off a girl with blonde hair and a bright smile holding the hand of a man in a blue suit with a trench coat and spiked hair. The Doctor watched as a younger version of himself swung the girls hand back and forth, exclaiming the planet they were on.
"Go talk to her," Rory said in a tone that didn't make it a choice.
"Rory I can't just- it's not that simple- she's with me. I can't mess with my own personal history!" The Doctor said frustratedly, he yearned more than anything to run and embrace her.
Rory was looking at the couple then to his Doctor, "You really love her," he said with a slight disbelief. If he'd ever seen an example of true love it was the Doctor and the girl he'd never met. The Doctor sighed deeply.
"Can I mess with your personal history?" Rory asked looking for a loophole.