The impenetrable white wall; the impossible barrier.

The Doctor sighed and shifted himself in his wheelchair. So much was riding on his ability to integrate his telepathic abilities into the Archangel Network, but though he'd managed the first few layers, a deeper connection remained elusive.

Whenever he tried to center himself, to meditate and focus, he saw it there in his mind's eye –the white wall. Torchwood's finest concrete, he mused, and it wouldn't matter if he resonated it from here till eternity, he could never break through it to the other side.

It was, he thought, the perfect fortress, built out of the very walls of reality to keep him out. The image was the epitome of despair.

He closed his eyes and tried again, blocking out the hum of the Valiant, the shrieks of the paradox machine, and Jack, in shackles, watching him from across the room.

Suddenly, the doors to the bridge swung open. "Have I got a treat for you two today," said the Master enthusiastically, walking over to where Jack was chained to the wall. "I've been saving it for ages."

The Doctor blinked his eyes open and glanced across the room to Jack. Oh, this wasn't going to be good.

"Go on, guess what it is," said the Master with a grin. "Ooh, you'll never guess. But go on; give it a try."

Jack and the Doctor both remained silent.

"Oh, come on, give it a go," said the Master. "Or maybe I should start taking pot shots at the maids again, eh?" He twirled his laser screwdriver.

Jack grimaced. "You've brought us cake?" he asked sarcastically.

"Wrong!" shouted the Master gleefully. He spun around and, just for fun, killed Jack with his screwdriver. "Well, fancy a try?" he asked the Doctor as Jack's lifeless body slumped against the wall.

The Doctor said nothing.

"You're no fun anymore," complained the Master, leaning over the Doctor's shoulder. "Still, I think you might have something to say before we're done." He gave the wheelchair a shove and sent it spinning. Behind them, Jack gasped, clawing his way back to life again.

"So," said the Master, "Now that we're all among the living, let me start by telling you a little story. When I was still playing my little human charade, being the good politician and all, I had a publicity event scheduled at the opening of a certain memorial." He bent over the Doctor and grinned. "For Canary Wharf," he whispered, sotto voce.

"A nice little memorial they'd built," he continued. "You ever been?" he asked Jack, who grimaced and nodded just once. "A stretch of wall with these little bronze plaques on it, one for each of the boring, little people who died, with their names and dates and a few sentences detailing their boring, little lives. So sentimental, these humans," he mused. "But imagine my surprise when I saw this."

H e reached into his coat and pulled out a plaque. He held it up so Jack could see it.

"And what does that say, Captain?"

Jack swallowed. "It says 'Rose Tyler.'" He glanced at the Doctor briefly, eyes full of apology. "I…I can't read the rest of it."

"Of course you can't, you repulsive freak," said the Master jovially. "It's written in Gallifreyan. For you to read it, we'd have to scoop out large sections of your brain and then rewire it to a much larger and more impressive supercomputer."

He leaned back against the console table. "The point is, it seems like someone must have come along and done a little personalizing to this particular marker. With a sonic screwdriver. I wonder," he said, giving the Doctor's chair a little push with his foot, "did you take the time to program in a special setting for etching bronze?"

He tossed the plaque, and it landed with a clang on the console table. "Well?" He looked expectantly at the Doctor. "Are you going to read us your little love note?"

The Doctor didn't say anything, just sat slumped in his hair. The Master sighed theatrically and picked up the plaque. "Fine, I'll read it then."

He cleared his throat, and pressed one hand to his chest dramatically. "'On Behalf of the Universe, an Epitaph to Rose Tyler,'" he intoned with mock solemnity.

"'Rose Tyler is clever. Her eyes see things that others can't: an excess of TV aerials; oddities of plumbing; and massive, radial transmitters.'" The Master paused and grinned. "Aren't you the poet? TV aerials," he snorts and shakes his head. "No doubt she'd be swooning."

He raised the plaque again. "'She sees fear of the child in the eyes of the mother; malice in the words of gaseous entities; and the hero in the heart of the conman.'"

Across the room, Jack flinched, and the Doctor's eyes flickered up to meet his. The Master noticed.

"Oh, was that referring to you?" he said softly. "Well, that'll teach you to be a hero to a girl with the power to make you immortal, eh? Or at least, THAT will," he added, killing Jack again for good measure.

"What?" he said in response to the Doctor's scowl. "Something you'd like to add?"

The Doctor stayed silent, however, and when Jack was conscious once more, the Master continued.

"'Rose Tyler is kind. One smile from Rose Tyler grants absolution. A word from Rose Tyler reunites the son with the father.' Oh, isn't that sweet," he murmured. "Really touching stuff, this. 'One touch from Rose Tyler teaches a Dalek mercy.'" At this, the Master paused. "Actually, that IS a story I'd like to hear." He quirked an eyebrow at the Doctor, but got no answer, so he continued reading.

"'Rose Tyler is brave. She converses with werewolves, unmakes false gods, and shouts down invading alien armies.' Blah, blah, blah. 'Rose Tyler looked the Devil in the eyes and sent him crawling back into hell.' Do you suppose she puts that on her CV?" he mused.

The Doctor didn't answer.

"'Rose Tyler is beloved.' Now, see, here's where it gets a little interesting because you don't really have any examples for this one. Beloved by whom, eh? Oh, go on, you can tell me." He slung his arm around the Doctor's shoulders. "Did you wuv her?" he asked, pouting out his lips. The Doctor closed his eyes, and the Master smirked.

"Can't you just shut up?" muttered Jack, unable to keep silent. The Master took another shot at him but missed his torso and scorched his arm. As Jack bit down a scream, the Master rolled his eyes and picked up the plaque once again.

"'When Rose Tyler falls—from barrage balloons or Justicia observational platforms; from the aftereffects of a psychograph or straight into the Void—there will always be someone there to catch her, because the universe will not stand for it to be otherwise.

"'And this leads to the last, and best, secret of Rose Tyler: Rose Tyler is alive.' Hmmm," the Master said, leaning over the Doctor. "Alive in a parallel universe, wasn't that it? You know," he said, sitting back, "she sounds like quite a girl. So I've been thinking – once my TARDIS is ready to travel, I'll see if I can't make a few modifications to pop over and visit her."

And at this, the Master's smile turned feral and cruel. "I'll be sure to give her your love," he whispered. "Repeatedly."

For the first time, the Doctor looked up and met his eyes. The Master was staring at him, looking for a sign of pain, searching for a crack in the calm façade. What he saw wasn't quite what he was expecting.

The Doctor was smiling.

"Yeah," he rasped in an old man's voice. "Good luck with that." With a chuckle, he leaned back in his chair, closed his eyes, and saw it there, once again.

The impenetrable white wall; the impossible barrier. The perfect fortress, built out of the very walls of reality, keeping her safe.

With a sense of peace, the Doctor centered his mind and felt another layer of the Archangel Network give way.