Disclaimer: I don't own it, none of it. Zero, null, nada. Except mistakes, they're all mine.
A/N: This is my first attempt to interpret some question that have been bugging me quite some time, as also my first published fanfiction ever. I know my logic may seems to have many flaws, and It's certain not bulletproof, but all this exaggeration I have to make, was simply to prove my final point. And maybe, I don't know to add some dynamic to the story. I'm not even sure if I myself believe, in what I've written.
Awful lot of running.
At the beginning of his journey with River, Doctor often wonder why they keep meeting each other in the wrong order. Of course, there was that time travelers stuff, with seems to be cause of that, keep being all confusing schumsing, and all that nonsense, which he refuse to believe. Everybody, well everybody who counts, knows that time can be rewritten. So why older version of himself wouldn't try. Surely this, future he must care about her enough, to try and keep her with himself, to try prevent her from traveling back his time stream. Even if he now didn't yet feel the kind of affection, which might cause him to take some radical actions, his mind was telling him that he was unavoidable going there, that he someday will be.
When he grew older, his relationship with River grew stronger, and so was his suspicions. Constant little voice in the back of the head telling him that something is not quite right, if not just plainly wrong. Why not prevent this difficult meetings, why allowed him to feel confused, and her to feel unloved. Is that really necessary? Maybe there is no other way, like some fixed point in time he has yet to uncover. But then, their story was getting thicker and thicker and thicker. And even after the final revile of the mystery, he couldn't see anything, any paradox, or TAS event collapsing, nothing. So he decide to stop wondering at all. Unsuccessfully of course.
Final dose of doubts arrived when their time streams stopped reversing. After helping to put her in prison, he broke her out of it the very first night, and continue to do so night after night. And then, except few minor incidents, but really they travel in time and space, who doesn't have incidents, he kept seeing her in proper order, never advancing, confusing, or spoiling anything. That was the ultimate prove, that they can do it, that they weren't bound to missing each other out. So why allowed this, what was so important, that after breaking so many others, he didn't break this one rule. He decided, that this time, he would brake it, not caring about consequences just would do it. He's done more risker thing to save few peoples in some towns on some planets, for god sake, what was so scaring about this sacrifice.
When he finally learned the reason, it was already too late. And it wasn't like he couldn't have notice it, like he inevitably had it coming. No, he was just too thick, just too preoccupied with thinking about himself, to look around and realize it wasn't about him. It was about her. It was her decision whether stick with older him or not, her who could break the rules and try to rewrite the time. The problem was not that she was afraid, or she wasn't aware, she simply didn't want to. And that's putting it lightly. The truth was that she just run, like a wind, like they always does. She know how, she learned from the very best how to do it. And what a better way to run from the time lord, than down his own time stream. If there was any place, she knows he wouldn't follow, that was it. He's own past. Because crossing own time line once, is one thing, but traveling across it, was something completely different. So she could run, with her head high, without any fear, without need to keep looking around the shoulder. Flirtatious, and confident as ever, the perfect disguise. And maybe if he once, just once stop thinking himself so damn clever, and look properly at her, he would saw what really glimpsed in her eyes for that splits of moments. He would realize it wasn't hurt that he saw, it was fear. And it was fear of him.