A/N: Did I ever mention that Dalek mucus has a pH of 2.4? Coincidentally, so does your garden variety white vinegar. (Also, please forgive my shameless pandering to the gods of continuity.)

All around them, the TARDIS was going haywire. Outside, all of Cardiff was shaking, shuddering with the force of the escaping rift energy. But the Doctor only had eyes for one thing: the hand of a killer, wrapped around Rose's precious, fragile neck.

At a nod from the Doctor, Jack set the extrapolator on the floor in front of the Slitheen.

"Stand back, boys," said Blon Fel-Fotch Pasameer-Day Slitheen with an evil grin as she tightened her grip on Rose. "Surf's up."

Just then, something caught the Doctor's attention. There was movement along the ceiling—the stealthy, slinking movement of something lurking on the arm of one of the coral struts just over where Blon and Rose were standing. As he looked upward, the Doctor saw a large, yellow eye blink back at him.

"Margaret," said the Doctor, suddenly cheerful. "Sorry, I've just remembered—did I ever introduce you to the fourth member of my little crew?"

With expert aim, Pedro the Dalek launched himself into the air and managed to land on the Slitheen's exposed arm. SPLAT!

YOU WILL NOT HARM ROSE! he thundered telepathically, and he belched out a huge wad of Dalek slime onto the Slitheen's bare skin.

"What the…" gasped Blon, but that was all she got the chance to say, as the acid-base reaction cascaded down her arm and into the skin suit. There was a violent ripping noise as the compression field failed. The last thing Pedro heard was a loud, muffled BOOM as the force of the explosion sent him flying across the room.

After that, it all faded to black.

As Pedro slowly blinked his way back into consciousness, the first thing he saw was the Doctor's face, looking down at him. He weakly stretched a tentacle out, and the Doctor met him half way with his hand.

"You really ought to rest, you daft little Dalek," scolded the Doctor, but he couldn't quite keep the grin off his face. "You got flung halfway across the console room. You're in the Med Bay, by the way."

TIME LORD... croaked the Dalek telepathically. DID ROSE…SURVIVE?

"Yes, she's right over there." The Doctor pointed to a nearby gurney where Rose lay with her eyes closed. At a flash of telepathic alarm from Pedro, the Doctor tutted. "No need to worry; she's fine," he said. "She just bumped her head a little when she was knocked back by the explosion. She's sleeping now."

THAT…IS GOOD. TIME LORD, I…AM…DYING…

"Don't be silly; you're not dying," said the Doctor with a roll of his eyes.

YOU MUST TAKE CARE OF ROSE…FOR ME…

"That's very touching," said the Doctor with a smidgen of sarcasm. "Pretty sure that's what I was doing before you came along. And in any case, I'm telling you, you're not dying. You're just a bit stunned, and I treated you with the dermal regenerator, so I had to give you a few drugs. They're just making you a bit loopy."

YOU ARE CERTAIN?

"Yep," said the Doctor cheerfully. "You're going to be good as new. No doubt you'll be lurking around my ship for a long, long time."

AND ROSE WILL BE FINE?

"She'll be up and about in no time, I promise."

Almost on cue, Rose groaned and rolled over. "Ugg, think I need a shower," she muttered, brushing at the Slitheen slime in her hair.

"You, me, and the TARDIS makes three," said Jack grimly as he entered the Med Bay. "That was one heck of a slimy explosion—it's gonna take forever to get all that Slitheen goo out of the grates. Still, it's better than us all being ripped apart if the rift exploded."

"Well, if she'd managed to open the rift, she'd have nearly pulled the ship apart. Any more stress on those panels, and it'd opened the heart of the TARDIS," said the Doctor, not entirely sure why he felt like adding that little bit of plot exposition. It just seemed…important somehow. "All sorts of odd and unlikely things might have happened in that case."

"Wow," said Rose. "That's strangely interesting information. I'll be sure to remember it for later."

"What I can't figure out is how the Doctor managed to stay clear of the mess," said Jack, trying to wipe his hands clean on a Med Bay towel.

"Superior reflexes," said the Doctor happily.

"Oh, shut it," said Rose, though she was smiling as she pulled herself up to sit on the edge of the gurney. "Being the farthest away from the blast probably helped, too. And how's Pedro doing?"

"A bit melodramatic, but otherwise fine," said the Doctor. "Clever idea, that, you jumping down on Blon's arm. She never knew what hit her. Literally."

"Well, anyway, all's well that ends well, I guess," said Rose as she hopped up. Then her face fell. "Oh, god, I forgot about Mickey!" She turned and ran out of the room.

"Don't worry, Doc," said Jack, moving to follow her. "I'll make sure she gets back OK. Just stay and keep an eye on your patient." The Doctor nodded.

Once Jack had followed Rose out of the Med Bay, the Doctor looked down at Pedro. "Well," he said heavily, "I s'pose I owe you my thanks. Who knows what might have happened to Rose without you there."

SHE IS VERY JEOPARDY-FRIENDLY, remarked Pedro.

"Yes, she certainly is."

PERHAPS…WE CAN LOOK AFTER HER TOGETHER.

The Doctor gazed down at the hideous, slimy, occasionally murderous abomination of nature who had just saved the life of the girl he loved. "Pedro," he said with a grin, "I think this might be the beginning of a beautiful friendship."