"You know," said Jack, gasping heavily as John Hart kissed him, "after all I've seen and done, I can't believe you're my worst fear."

"Worst fear? I'm touched," said John Hart. He ruffled Jack's hair. "Knew you went in for the kinks, but I never thought it scared you."

Jack's eyes went to the sky. "There's stuff out there I've faced that still gives me nightmares," he said. "The Velzindrious Echop. The Iploti on that Corona planet. The 456." He shook his head, eyes turning back to Hart. "Not you. You're just a pain in the ass."

"You bet I am," said Hart, grabbing Jack's rear.

Jack shoved him away. "Makes me almost think you're real," he said, "and on one of your 'side-trips'. Those Ecwousi sisters caught up to you, yet? They were supposed to have pretty comprehensive psychic powers."

"Maybe what you really fear," came a voice to Jack's right, "is someone from your past showing up in your present."

Jack spun around.

Then groaned.

"Suzie Costello," Jack said. "I wasn't afraid of you, either."

Suzie raised up the resurrection gauntlet, on her hand. "Scared of your past showing up and biting you in the ass, though, huh? Not like you used to be squeaky clean."

"That's because every time my past shows up, things go to hell." Jack shook his head, and pushed past them. "Now get away and leave me alone."

"Past always catches up to you in the end!" Hart shouted after him.

Jack blocked them out.

As he stormed away from them.

"How about the Uciko of Malterna?" Jack muttered, hands clenched into fists. "The Dreaded Barbarachi? I got trauma enough to last me lifetimes — and this fear-goblin can't even get inside my head enough to see…?!"

"Good point, Captain!" came the Doctor's cheery voice. "Top marks! Gold star!"

Jack jerked his head up, to find the Doctor, Seo, and… someone in black clothes with a pointy beard and malicious smile… all headed towards him.

The Master, the Doctor had said.

Must be another incarnation.

"See, I can understand how the events here would create that destroyed future," the Doctor explained. "Simple! My greatest fear, turning into Seo's greatest fear. Feed them together and — if I hadn't been quite so brilliant and figured it out quickly as I did — nearly every planet after this point would have been turned to a burnt-out husk."

The Master scoffed at the Doctor's assertion of his own brilliance.

But remained silent.

"But there's something very wrong with Jack, and I can't help but think it's related," the Doctor concluded. He handed his gizmo to Seo. Then spun back, and grabbed a black tube out of the Master's hands. "First things first, though. Now that we've modified the Tissue Compression Eliminator…"

He tossed the TCE to Seo, who caught it. Quickly stuck it in the Doctor's device, then pressed the button.

Jack started backwards, as he noticed something twitching in the air.

Something that had once been microscopic, now growing, ever larger and larger, into floating green globs.

Writhing, floating green globs.

"Ha!" the Doctor cried, clapping his hands. "Big enough to see you, now!"

Seo made a face. "We've been breathing in these things, ever since we got here?"

"Yep," said the Doctor. He turned to the Master. "And I'm guessing you recognize them."

"Fascinating," the Master said, studying the green globs, intently. "Havchornom Spores."

"Exactly what I was thinking," the Doctor concurred.

"Quite impossible," the Master muttered. "And yet—"

"You're forgetting where we are," the Doctor countered. "And what you did, a million years ago."

The Master paused. "Ah. I see."

Jack and Seo looked at one another.

Neither any the wiser.

"Huggy Chummy Spores?" Seo asked. "What are…?"

"The Havchornom," the Master cut in, impatiently, "are a race from the Dark Times. They allied themselves with the Great Vampires, and were completely and utterly wiped out by the Time Lords."

"Or so the story goes," the Doctor amended. He bounced on his toes. "Of course, since one of the Great Vampires managed to flee to another universe… it's entirely likely that some of the Havchornom escaped, too." He shook his head. "Nasty bunch."

"They escaped out of the universe, and now they're trying to get back in?" Jack guessed. "Is there some kind of rift or gateway, here, that could…?"

"The planet Ariffildos had another name, once," the Doctor cut in, gesturing around them. His eyes fell on Seo. "Bytopin."

Seo's eyes went wide. "Bytopin! But that's in the Irkoli—!" She looked between the Doctor and the Master. Then pointed at the Master. "He let the Havchornom back in!"

"Almost," the Doctor said. He grinned. "I have a feeling that when the Master opened that dimensional fissure, they did try to invade. But you, Seo, sucked them right back out of the universe, again! Brilliant trick you did with the black hole."

Seo didn't seem placated.

Her eyes still fixed and glaring at the Master.

"But even if the Havchornom didn't come through, their spores did," Jack guessed. "They wound up concentrated on the planet Ariffildos — and Seo activated them just by showing up here."

The Doctor steepled his fingers in front of his face, thinking it through. "Yes, I suppose…" Then, with a glance at Jack, "You didn't suggest she come here, did you?"

"No," Jack replied.

"Terazina told us where and when to go," Seo added. "Except then she warned me not to come. But I didn't listen."

"Tera—? No, never mind. Topic for a later time." The Doctor brushed his fringe out of his eyes. "Most important now is the Havchornom. If they've infected the Irkoli galaxy with their spores, they could do untold damage!"

"But only if I show up," Seo said. "I'm what's making these illusions real!"

The Doctor shook his head. "Believe it or not, monsters appearing out of thin air is the least of our problems with the Havchornom, Seo."

Jack nodded, slowly. "I'm guessing this is where I come in, then. And the explanation as to why these spores aren't able to get to my fears, properly." Prepared himself for the worst. "So. Out with it. What else do these Havchornom do?"

"The Havchornom don't just manipulate thoughts," said the Doctor. "They manipulate time. In particular, they're very good at manipulating the recent past."

"And Jack's…!" Seo realized.

"…a fixed point, yes," the Doctor agreed, giving her a proud pat on the back. "Which is why he isn't affected in the same way we are."

"Manipulate time… how?" Jack asked. "If they can't mess with fixed points… we're okay. Right?"

The Doctor sighed. "Trouble is… they use their manipulation of the recent past as a weapon. Whatever plan we come up with against them now, for instance, they'll know about it. And already have countered it."

"Correct, Doctor," said the Master, a stazer suddenly in his hand.

He fired straight at the Doctor.

"Good one, Climp," said one of the Havchornom, watching it all play out in the center of the table. "A little predictable — the Master trying to kill the Doctor. But the classics are always the best."

"The Doctor has such a fascinating mind," said another, twisting around his head to peer more closely at the image. "Always twisting and turning the possibilities. And so far from seeing the whole truth!"

They were interrupted by the sound of the wall being vaporized, beside them.

And a tall blond girl with a gun stepping forwards, leveling it straight at the three demons. "One chance. Tell me what's going on and how to stop it. Or you get very dead very fast."

The three Havchornom seemed surprised.

But remained perfectly calm.

"I'm not messing about," Jenny warned. "You've got until three." Charged up the gun. "One… two…"

Buffy put a hand on Jenny's arm.

"They're… not scared," Buffy pointed out. Gesturing at the three Havchornom in front of her. "And the only people who aren't scared of getting shot when there's a great big huge gun stuck in their faces… are the ones who know that they're not actually in any danger."

Jenny paused.

The Havchornom just smiled, with jagged, sharp teeth.

"So what's the gimmick?" Buffy demanded of them.

"Our future selves will reach back and manipulate this moment so it goes in our favor," the Havchornom replied. They gestured towards Jenny. "The Gallifreyan should know better."

Jenny frowned.

Lowered the gun.

"You can manipulate time?" Jenny asked. Her eyes drifted to the image in the center of the table, of the Doctor, Seo, and Jack. "The catastrophe. All those planets, across all those different times. And one moment when it all…" She shuddered. "What did Dad, Seo, and Jack do?"

"Ah," said one of the Havchornom. "The Gallifreyan's worked some of it out, at last."

Buffy looked between the Havchornom and Jenny.

Feeling lost.

"But not all," another Havchornom continued. "You still blame us for the catastrophe."

Jenny shook her head. "You mean you're not responsible for the catastrophe?"

"We must feed to renew our strength," the Havchornom said. "Large temporal manipulations across the Gateway are still beyond us. We could not create the catastrophe if we wanted to. But the fear and turmoil caused by the catastrophe, amplified by the conduit Buffy Summers, will give us the strength we need to open the Gate and return."

"Yeah, good luck with that," Buffy snapped back. She surged forwards, grabbing one of the Havchornom up by the neck and slamming him against the wall. "You used me to put my daughter in danger. I don't get what this whole 'catastrophe' thing is, or what the hell you guys are talking about, but you're so not using me to unleash hell onto an unsuspecting universe!"

Jenny stared at them.

Suddenly silent.

"You can't harm us," said the Havchornom Buffy was threatening. "We manipulate the recent past. We can always create something to our advantage, to gain the upper hand in any situation."

"That doesn't work if your future selves are dead!" Buffy shouted. Reaching down for her concealed knife. "And if you don't tell me how to save Seo, I'm gonna cut you down to—!"

She paused.

Then swore, as she realized she'd already lost the knife, earlier.

"Okay, I get it, manipulate the recent past," Buffy said. Mind racing, as she stepped away from the Havchornom. "So I'm guessing if I try to punch you, you'd just alter the events of my recent past so I got a broken arm or whatever, and couldn't."

The Havchornom nodded, smiles on their faces.

"And your injuries, within the chamber, are shared with your daughter," said a Havchornom behind Buffy. "Any broken arm you got, due to your aggression right now, would only harm her, earlier."

"Yeah, yeah, I can take a hint," Buffy grumbled. She backed towards Jenny, still set in a fighting position. "But if you think I'm gonna get you through the Gate, you've so got another… thing…"

Buffy stopped.

Then turned around, to face Jenny. Who'd gone very pale. And very quiet.

"Jenny?" Buffy asked.

Jenny blinked. Then tucked the gun under her arm, and turned. "Let's go."

"What? But these guys are still using their spores to end the universe and stuff!" Buffy insisted. "We're so not about to—!"

The ceiling collapsed, just in front of them. Weakened by the vaporization of the wall.

Their exit was blocked.

Jenny gritted her teeth. Then spun back around, to face the Havchornom. "You think you're so clever, don't you?"

"Tell Buffy Summers the truth," the Havchornom said. "Tell her what you've worked out."

Jenny instead raised up her gun, to fire at them.

But the gun malfunctioned, and died in her hands.

"Tell her," another Havchornom hissed, creeping towards them like a predator stalking his prey. "Tell her what she should already know."

"So you can have the satisfaction of feeding off her misery?" Jenny shook her head. "I don't think so."

Buffy felt fear rising up in her throat.

The smiles on the Havchornom's faces growing wider, as they felt her fear mount.

"What… are you talking about?" Buffy said, struggling to control her emotions. "What's going on?"

"Just leave her alone," Jenny told the Havchornom. "You're going to get enough from her when she finds out. You don't have to rub it in."

"Rub what in?!" Buffy glared at them. "Is anyone going to tell me what you're talking about?!"

"We manipulate the recent past," said one of the Havchornom, coming towards Buffy. "Even outside the Gate, to some extent. You agreed to join us in our manipulations."

"Yeah, because you said I can save…" Buffy stopped. Then looked over at Jenny. "Wait. The Havchornom manipulate the… past, outside the Gate?"

Jenny didn't answer.

"What happens next to Jack, the Doctor, and Seo… it's already happened," Buffy realized. "Jenny stepped into this time zone to save me. We're both involved — we can't go back in time to Ariffildos and change things, anymore."

The Havchornom gave coarse laughs.

"But that's fine," Buffy decided. "The Doctor's there. He'll figure everything out and save the world without batting an eye! It's not like…"

"You think you can distract us while the Doctor saves the day?" said one Havchornom.

"Stupid little human," said another. "The catastrophe looms. What do you think our game really was?"

Buffy glanced back at the center of the table.

The Doctor sharing his theories about the nature of the catastrophe with everyone else.

"Your spores and monsters and stuff have nothing to do with the catastrophe," Buffy realized. "It was all a distraction. A way for you guys to feed and make sure the Doctor can't outsmart you before the real catastrophe happens. And you gain enough power, feeding off that, to exit the Gate."

The Havchornom applauded Buffy.

"The human has a slow mind," the Havchornom noted. "But she does get there in the end."

"The catastrophe's already happened, hasn't it?" Jenny guessed. "It happened shortly after I got here, when I was still trying to track down Buffy." She took a long, deep breath. "What is it?"

"Can't you guess?" said one Havchornom.

"You guessed before," said another. "It's why you were so frightened to go to Ariffildos in the first place."

Buffy still felt totally lost.

"Look, you're gonna have to give us way more information if you want us to guess what destroyed the future," Buffy told them. "I know all the universal catastrophes. Hellmouths opening, portals being created, or…" Her heart raced. "Is it Seo? Did she go into weapon-mode again?"

"There was no one catastrophic thing that destroyed all those planets," Jenny said, very quietly. "That… isn't how it happened."

Buffy turned to Jenny.

"I told you — I did the research," Jenny said. "I thought it was like you said — one villain arising, or one evil force being unleashed or… one big bang that destroyed everything." She shook her head. "But… that wasn't what destroyed the future."

"Not a new presence," said the Havchornom. "Just the absence of two sisters from history."

Buffy felt something inside herself tighten. "No…"

"That's why I didn't want to go to Ariffildos, in that year, at that time," said Jenny. "Because that's where time changes. So that Seo and I are killed. For good."