"So I'm confused," states Amy, swinging her legs back and forth from her perch atop the med-bay's counter.

The Doctor would have had something pithy to say to that, but as he's distracted all he manages is an absent, "Hm?"

Amy hops down from her perch and moves to stand beside the Doctor, who's hovering like an anxious parent, coat and bowtie askew, over the unconscious redhead lying on the raised bed.

"We've been to two planets now where they've tried to kidnap Donna. Both times so they can claim to be the 'home of The Most Important Woman in the Universe.'"

"And?" prompts the Doctor, still distracted, gently running his fingers through Donna's hair, a bright halo of curls on the pillow. He fights a vicious short-lived internal argument before carefully brushing his thumb across her left temple to take a quick peek, confirming the sonic's reading that her deep sleep is due to exhaustion and not a concussion or worse. He knows he shouldn't, but he can't take any chances. Not with her, not since he's lost her once before.

Her mind is quiet and at peace, only recuperating from stress and dehydration - dehydration from being locked up in a temple where the alien species didn't realize humans needed water regularly, and stress from being abducted and the subsequent running as they rescued her. Reassured, he immediately lets go, feeling guilty even though he was only doing a quick check. Donna was still extremely wary around him and wouldn't normally allow him to touch her face...not since the last time.

"Doctor!" Amy's impatient voice cuts through again.

He sighs, resolutely shoving his hands in his pockets, and forces himself to turn away and face Amy. "I'm not quite sure what your question is, Amy."

"Well, if you've been running amok through all of space and time and you have a big brain full of useless information..." She ignores his indignant squawk of protest and forges forward, "useless informationabout every planet's history we've been to, then how is it that you didn't know about Donna before?"

He stares at her owlishly for a second. "Know about Donna before what?"

"Before! Before the 'Most Important Woman in the Universe' bit! Shouldn't you have known all about what was going to happen? I mean, I haven't been traipsing along with you but a few months and I've already heard about it in several galaxies. Shouldn't this have been common knowledge to you before it ever happened?"

"Ah, Amelia Pond," and now he smiles, because it always pleases him when his companions ask something clever. "You smart girl, you."

"Yes, I know," sniffs Amy, with much dignity. "Now explain it to me."

"Well, you see, Donna saving the Universe hadn't happened in the past when I was in the future. Once it happened in the past, then the past future changed to the now future."

Amy's head has tilted so much to the side that it's a miracle she hasn't tipped over. "When what now? What the hell does that even mean?"

"Time isn't linear, Amy. Temporal events are always in flux, with some being more important than others. Some are so important that once they happen, they become fixed - nothing can change them again - and they consequently send a ripple effect through the future and the past, changing everything permanently."

"Umm...so, what you're saying is then," she sqwinches her eyes shut, hoping it would help her brain put things in order, "that although everywhere we go now seems to know about her, you hadn't ever heard about her before when you were there...in the future. Um, past. Wait, no, future."

"Right." He finally gives in to the urge to turn back to Donna, to smooth her hair once more - before she has a chance to wake and tell him to take his "preppy regenerated paws off her."

Amy watches the Doctor watch Donna. She had once thought (bragged, really) that she knew him as well as anybody could, but...there's a deep pool of hidden emotion there that he never lets shine through, until you catch him looking at Donna. Then it's all in the eyes, all this ancient guilt and sadness and wanting in those too-young eyes.

"But now that it's happened, there's not a moment when I didn't know about The Most Important Woman in the Universe. That fixed point changed my own knowledge too, you see, just like it has changed all the history books. But in my new memories of that knowledge, I never knew her name...never knew that that most important woman was Donna Noble." He's slowly been leaning ever closer to Donna during this explanation. One of the Doctor's hands is again buried in Donna's hair, the other seeking out Donna's limp fingers to tangle with his own, and he's curving over her as if he's braced to throw his body over hers in protection against any sudden threat.

Amy's sure he's not even aware of it. Completely clueless, most like. Men, muses Amy. They're all idiots, even the geniuses.

Because any half-wit can see that Donna's the Doctor's magnet; he can't help but gravitate towards her, touch her. Since Donna's been back on the TARDIS Amy's lost count of how many times she's watched him reach out and then pull back. She's almost a little embarrassed to be in the room, actually. She's pretty sure he'd be crawling into bed with Donna right now if he weren't afraid she would cause him bodily harm if she woke up to him there with her.

"I think you did, Doctor," she tells him finally, as she starts to back out of the room. He turns his head only slightly, inquisitively. "I think you knew she was the most important woman...in your universe, at least."

And Amy leaves to search out Rory while the Doctor tries to figure that one out. She hopes the Doctor will have the guts to crawl into Donna's bed even if she slaps him for it later.