If there were one thing the Doctor understood without question in this new world, it was how justified Rose was in her anger at him. He'd been a high-handed old fool again, leaving her behind. He should have waited. At the very least, he should have said goodbye. She had deserved some sort of closure. Still, he wasn't certain he could have managed a life with her and his other self in the TARDIS. It was bad enough, watching the woman he loved grow old while he continued on, ageless by comparison to a human's lifespan. How much worse would it have been to watch his other self fade, as humans did? What else could he have done? He didn't know, and it didn't matter, not anymore.
Rose, brilliant, wonderful Rose, had given him more than he deserved by allowing him back into her life. He wondered if he were taking advantage of her kindness by accepting that invitation. Would it do more harm than good to attempt to reconcile all that had come between them? He didn't know, couldn't see that clearly when his own personal timeline was involved.
"She's not the one who needs to come around," he found himself saying. "It's me. I'm the one who made the mistakes. I'm the one who needs to make amends."
When his other self stepped forward to help him with the equipment, the Doctor silently stepped back, sore arm cradled close against his side. "Do I really have a choice?" he said, flashing a tired smile at his counterpart and the offer of assistance. "Another second or two in that booth and I'd have shown up here already regenerating. Isn't that so?" He cast a glance at the readouts and shook his head. Everything had happened so quickly after he'd opened the door to the chamber. He'd done his best to simply do, not to think. No chance for regrets, that way, and no chance to yet again take the coward's way out. For a moment, he felt sympathy for his older self. What he must have gone through, before he changed. The Doctor was sick at the thought of it.