Once, when Daniel was ascended, he met a girl named Rose Tyler. He was on Earth to look in on Jack, because he worried, and he felt her halfway around the world, and he was curious, because Ancients didn't visit Earth often. Or even parts of them, which was properly what this Rose was--a part of herself--she was bending spacetime in a way he frankly didn't know how to yet, mostly because, frustratingly, no one would teach him anything he hadn't already absorbed from just being and encompassing existence.
Daniel said, "What are you?"
Rose said, "I am the I am."
Daniel said, "Well, so am I. But what are you doing?"
"Watching my mum," said Rose Tyler, which was when Daniel realized that even in some non-corporeal plane, she was talking with a London accent.
She was human, or had been once, the same as Daniel. She was there for the same reason Daniel was.
Except she wasn't all there. In fact, such a tiny sliver of her was there that Daniel suspected that the rest of her was not all one place else, but rather in tiny slivers permeating creation.
"How can you do that?" Daniel asked. He was tempted to wave his hand through the dimensions of her that should have been there and weren't, the same way Jack threw shoes at him to prove he wasn't corporeal. "Can you teach me how to do that?"
"No," said Rose. "I haven't the time. I've all the time in the world, and no time at all, and they would never let you do what I'm doing." She laughed, a desperate, teary laugh, and said, "They would never let me do what I'm doing if they could stop me--he certainly wouldn't want me to! But they opened the door."
She turned to give Daniel her full attention, then, and it was like a light being turned on. She glowed with a radiance that even Daniel couldn't match. "You want to know why they won't let you do anything," she said. "It's because they did something, once, they used their powers, changed the cosmos, remade it--and wiped themselves out of existence. They're not non-corporeal because it's some enlightened state of being, because it's not. Even I have a body, it's just not here. They don't have bodies because they aren't. They erased themselves. They're just ghosts, now, and they're afraid to change things anymore, because what if they manage to make things worse?"
Daniel stared. This was the most plausible explanation--actually, the only explanation--he'd ever gotten for why the Ancients refused to change things. He said, "Is that all I am? A ghost?"
She tilted her head, or at least, this was the way Daniel perceived her study of him. Her eyes were lit gold, but it was a warmer color than a goa'uld's. "No," she said, at last. "You have a body, too, though I can see why you would rather not be in it. I can fix that for you, if you want, so that you have something to go back to."
"You can," Daniel said carefully.
Rose shrugged. "Well, if I'm going to rewrite the universe, anyway," she said, "I don't see why not."
She put her hand through him, but it didn't feel like co-existing with a solid object like a shoe. It felt like she was touching him, and she twisted something, and there was a moment of puke-your-liquid-guts-out, bleed-your-melted-skin-off pain, and then there was a sense of reality that he hadn't felt since he'd ascended, and had just thought that was what being ascended was like. He looked down, and Rose's hand wasn't in him, it was resting lightly on his chest.
"It was very nice meeting you, Daniel Jackson," she said. Her radiance was starting to flare.
"Wait," said Daniel.
"I'm sorry," she said, too bright to look at. "I don't have any more time."
The world went golden-white, and then she was gone. The entire conversation had taken less than five minutes.
Daniel met her again, from time to time, or other slivers of her, but she never spoke with him for longer than a few minutes. She never quite seemed to recognize him when they met, but she always called him by his name when she left.
Eventually, Daniel realized what she had meant by all the time in the world, and no time at all. She was using her ascension to encompass more than all the universe: all of history and eternity were hers as well. But she was only experiencing that I am the I am for an instant in subjective time.
And every time she went up in that blaze of light, she was dying, he realized. Whatever she was changing, she was dying to cause it.
It took Daniel a long time--relatively speaking; months even--to figure out what he would die to burn out all his power changing.
And then he didn't die.
If he had remembered anything of what it was like to be the I am, Daniel might have gone looking for Rose Tyler, to see if she had really died when she ceased to be all things, or if she had only gone back to her singular, linear, mortal form, as he had.
If Rose Tyler had remembered anything of what it was like to be the I am, she might have gone looking for Daniel Jackson, to see if he had made up his mind to stop being a ghost and live.