They were safe. That's what mattered, right? At least, that's what the Doctor thought mattered at the moment. She was smiling, right up until River asked how long.
She had to think. It hadn't actually been that long, had it? Let's see...after Clara but before Bill, right? Yes. "Few years, actually."
There was a hint of sadness in her voice as she thought of her past companion. Another tragic end. Wasn't it always?
"I changed just about two or three years ago, probably saw you a couple of years before that. A blink and you'll miss it, really." Except not.
It had been so hard leaving River on that planet, watching her watch the towers. An endless night. She stared at her now, smiling at the memory.
"So...where should we go? Oh! Should you meet the fam??"