Oldest cliff face in the universe. What language could be engraved in letters 50 feet high that no linguist, in the billions of linguists over billions of years, could translate?
He had originally thought the message would be written by an obscure little world in a tongue forgotten long ago. They themselves might not speak it anymore, the way rare Time Lords knew the lost language of Old High Gallifreyan and rare humans knew Latin and even rarer were those who could read Tacitus.
But the Doctor began to suspect something else and it had to do with two women in his life -- well, one in his life and one creeping in whom he highly suspected would be just as big in his future.
As soon as he got back in his ship, he went to the console and gave the time rotor a good glare. “Did you and River make up that language?”
The Tardis gave some lights a twinkle and a few warbles out of her speakers. He guessed this meant, Maybe, but I’m not going to tell you just for the love of watching you stew or I happily choose to ignore you.
When he saw River, he tried again with, “You graffitied the oldest cliff face in the universe.”
Her reply, “You wouldn't answer your phone,” sounded suspiciously like chiding him about refusing to answer a call, and her own way of saying what the Tardis had.
It would be just like both of them to do it, for the sheer fun of all those people trying to create a translation matrix that existed only with them.
Just as important to them: no one could see what was for his eyes only.
That would explain why his ship hadn’t translated the Ancient Greek containing his Academy name. River knew the Tardis would keep that private too, so they could leave it up to him if he wanted to tell Amy.
He hadn’t. He wasn’t quite ready to share even that name, not yet. But River knew it. She knew every one of his names, but never broke his privacy in telling anyone else. She protected it every time she used one, even when calling him across time and the universe. First in Old High Gallifreyan on a home box in the Delerium Archive, the largest museum in the universe, and now this.
Wait a minute, he wondered in the back of his mind, how did River even know about the unanswered call? Was the Tardis actually phoning River? If that was true, he didn’t stand a chance.
He tried to get an answer out of her again as the Romans brought up their mounts.Her only response: “Try not to fall off the horse, Sweetie. We can’t afford to lose any time by going back for you.”
Who was she?
Yet another puzzle wrapped up in the overall enigma that was River Song. Except now... well, he was still frustrated, of course, that he didn’t know something that was obviously so important. But not completely aggravated anymore; now the riddle held a crumb of being intriguing. So his smile held that grain of “I’m impressed”. She was clever, intensely clever, so she knew he’d love these messages meant only for him in languages intended just for his eyes. She wrote not just Gallifreyan, but Old High Gallifreyan, and now in a dialect only the Tardis could tell him.
Mad blue box.
She and her secrets were maddening. He should keep running from her like he first said he would at the Byzantium. But that idea had rightly died a quick death.
By the end of rebooting the universe, she said, Yes.
He said, Nah in response to I’m sorry, but that's when everything changes.
How he looked forward to it.
He sought her out now instead of staying away until he was summoned. When the Ponds came back onboard right after their wedding (creating River, but who knew that except the woman herself?), he seized the nights to fall for Doctor River Song. He gave her what he gave no one else who sought or held his love. (Well, he had done it for his wife back on Gallifrey. Because a husband should show his spouse how much he appreciated that they had picked him.) He dressed up for River: he wore his dinner jacket to take her out. He wore his top hat and tails when he escorted her to parties and adventures, which were very often combined. He never changed out of his regular wear for someone, only for something that required it.
But one night, it was, “River! I’ll see you later! Tell Marilyn it’s too late, she'll have to use the biplane.” He did a little dance as he left the door, because who wouldn’t after a date with River Song?
Another night, it would be calling out through the Tardis door, “River, we got the wrong fish!”
Amy caught on to it right away. “Wait, you’re dressed up. You never dress up. Was River at the party?”
Of course he denied it. Because... because of reasons. Like he only wanted River to know it at the moment.
Then he completely gave himself away when Amy asked, “How is she?”
And he replied, “Fine.”
Ugh, the all seeing Pond.
Dressing up first said, Okay, you can drag me into things. Well, not drag because I came here to see you. Then at Berlin it had reached the level of, See how you hold my hearts, and, at last, it meant, Only one person held this unique place before you.
Of course Amy guessed it all the way back at the Byzantium; Rory followed close behind. They were the Ponds, and oh, River was Melody and Melody was a Pond too. She was them and she was the Tardis, who made up languages with her.
But only he and River spoke this one, as it should be. After all:
"That's between her and me, eh?"