"Come along, Pond."
He never calls her Amy. Not really.
Sometimes there are slips of tongue, but for the most part it is always Pond.
Never Amelia either, because his fiery companion would pitch a fit over that. She didn't want to remember those days of her childhood; the waiting and hoping, looking to the stars, that fairy-tale girl who didn't make sense. He still remembers her this way though. It was only yesterday for him, literally.
He'd crash landed into her life and changed it irrevocably.
She was Amy now.
He couldn't bring himself to call her Amy though, despite her insistent urging. That was just a name she choose because she was tired of waiting, tired of being disappointed- because he had disappointed her so many times over. She gave up that childlike faith and hope, and now she was different. Forever.
Amy was a name that held the tiniest bit of anger in it; but it was there, that anger towards him and all the disappointments he'd let slip into her life.
Amy was a new name for a new girl, the one he'd helped create, the one who kept people at arm's length, building walls around herself to keep her heart from breaking. He'd helped her form her own prison around herself, and how he wished he could fix that but there are some things even a Time Lord had no control over.
Amelia was a sweet child, who looked up to him and thought he would never hurt her.
Amy knew better- though she still followed him, she knew better.
There were times when he couldn't bare to think of all the damage he'd done her, times he just wanted to turn back the clock and fix everything, but he didn't want to look at the truth too clearly- because it was like starring at the sun and he felt it would burn straight through him if he were not careful.
Those were the days he called her Pond.
And she let him.
It was their unspoken compromise.