Author's Note: I own nothing.

17 Old World

Kai rolled into a summersault, arms tucked around her head to protect herself from the fall. She crashed into something wooden and grunted in pain but managed to stand mostly intact, just a few splinters here and there. She pulled a flashlight out of her belt and flicked it on as her badge began to beep. She pulled it out with her free hand.

"I'm ok." She answered the call and her grandfather let out a breath.

"Good, the mechanism is stuck, we may be able to jimmy it open on our side but it's risky. It could cause a tunnel collapse." Kai shook her head.

"No! I'll find my own way out." Max Tennyson's voice came over the com in her badge.

"I'm sending Jen to help you. She should be there in a moment." As he spoke frost rimmed part of the floor and Jen's alien form rose through the brickwork.

"Yep, moth-girl is here." A hefty sigh sounded through the insectoid mouth.

"Big Chill." Jen muttered as she wrapped her wings around herself like a cloak. Kai grinned slightly.

"We'll figure a way out." Jen leaned closer, ice cold breath whispering along Kai's arm.

"I found something deeper in. I'll take Kai to check it out before we head back up." Before Wes could speak Max's voice sounded again.

"Sounds good. Keep an eye out for other traps." Jen nodded and green lights flashed as she turned back to normal. Kai glanced at her as she pulled a small bag off her shoulder.

"Where does that go when you transform?" Jen shrugged.

"No idea." She rummaged for a moment before she pulled out what looked like a glowstick. She cracked it and shook it, it lit up a bright white illuminating the hallway they were in like an actual lightbulb. Kai flicked off her flashlight.

"Handy." Jen nodded and stepped over to the boxes Kai had crashed into. She brushed the moldering wood off the contents.

"Armor." She pointed out. Kai nodded. It was rusted and some of it had completely fallen apart, just piles of red rust but the larger pieces were still identifiable. Jen frowned and brushed at the rust on one of the breastplates. "There's another symbol here, some kind of circle. But it's too damaged to make out what it is." Kai nodded.

"You said you found something?" Jen nodded shaking her head as she stepped down the hall.

"Yeah come on." They made their way down two flights of winding stairs. Kai frowned.

"This is almost like a tower. I think you're right this was a castle." Jen nodded.

"I'm right a lot more than people give me credit for." Jen snipped and Kai frowned. She remembered Jen being a lot more friendly last time they'd seen each other.

"Did I do something?" Kai asked. "You seem really… tense." Jen glanced over her shoulder then shrugged.

"Guess I'm just untamable." That comment slapped Kai in the face with a realization that maybe she and Jen hadn't exactly parted on the best of terms. She was silent for a moment.

"Look Jen I'm sorry. We were kids…" She fell silent again as Jen shook her head.

"No I get it. We were kids but I'm not a toy." Kia nodded.

"I know that, I am sorry." Jen paused on the stairs and nodded looking back at Kai.

"Apology accepted." Kai smiled and held out a hand to Jen, she took it and shook it once. "Come on, it's just up ahead." Jen led her off the stairs and down a short hall before turning into a large room. It looked like it might have been a library at one point but the majority of the books and scrolls had rotted, not leaving much behind but a bad smell. In the center of the room though was something very out of place. An energy dome sat covered in dust but still active. Kai stared.

"How?" Jen shrugged.

"No idea, the Knights have always been good at stealing alien tech and even sometimes figuring out how to use it. That's what I was looking for, sometimes their more dangerous traps are automatons, alien tech that's hard to take down in close quarters. I didn't find any of that, actually this is the only piece of alien tech I could find. The fact that it's still working is pretty impressive." Kai nodded pulling her brush from her belt.

"You're not wrong." She made to brush off the dome but it flared and Jen pulled her back, as the dust flared into small flames leaving both girls coughing from the smoke for a moment. Jen waved it away and looked over the dome. She frowned. It was clear and beneath it were two perfectly preserved books. The top one was simple leather embossed with the Forever Knight sigil. The other was under the first but was bound in green leather. They were standing on a perfectly preserved table, carved to appear as though the legs were the Forever Knight sword. But this one was slightly different. This one had that same circular symbol in the hilt that the breastplate upstairs had. Jen blinked and stepped closer to the table.

"That's not…" Kai was frowning too.

"It looks like it is." They exchanged a glance before looking back at the circular symbol. Inside the circle sat an hourglass. It looked like someone had carved a Plumbers badge into the wood. "That can't be coincidence." Kai said shaking her head. Jen nodded.

"The same Galvan writing on two Forever Knight tapestries now Plumber symbols, no way is it a coincidence. Any ideas how to bust this open?" Kai pulled some tools from the pouches on her belt. She circled the dome for a moment before frowning.

"The projector's inside, I can't get at it." Jen leaned forward and frowned as she ran a hand through her hair.

"Maybe we can move the whole thing? Maybe Big Chill can freeze it solid first." As she let her hand fall back to her side the Omnitrix came close to the field and the dome flared again before flashing green and vanishing. Jen stepped back in shock then blinked down at her wrist. "What?" Kai shook her head.

"How did you do that?" Jen shook her head.

"Wish I knew." Jen stepped to the table and picked up the book on the top She blinked as she spotted the book underneath. It too had the Plumber symbol on it though this was carefully embossed to be even more eerily accurate than the one on the table. She slipped the first book into her bag without looking at it too closely and picked up the second one. There was a click and Jen swore under her breath as cracks opened and water began to flood into the room. Jen spotted a glowing symbol on the wall as she shoved the book into her bag. Jen reached under the table and snatched up the dome projector, Kai grabbed her arm and both girls ran for the stairs as the water began to rapidly rise.

Ethan frowned as he scanned the last tapestry that wasn't buried under the rubble. It had been a while since Kai had fallen through the wall and Jen had gone after her. They hadn't called back on coms since but that was pretty usual for Jen, she didn't tend to check in unless there was a real emergency. Which was why he frowned when his badge beeped. He answered quickly.

"Ethan speaking."

"Ethan! Get out! Get everyone out of the tunnels! Now!" Ethan turned to the others but they were staring at the wall of rubble behind him. He turned and looked down as water leaked out of the cracks between the rocks.

"What about you?" Ethan demanded as Pierce grabbed his arm and dragged him down the hall as Max and Wes began to call for the evacuation of the rest of the tunnels.

"I can get us out just go!" The call cut off and Ethan turned and joined the others as they raced out of the ruins and back to the surface. Ethan looked back at the site as water bubbled out of the tunnels.

"Everyone else is out!" Wes called out as he counted heads. Max pointed out at the site as a small section of the ground began to smoke before melting apart and disgorging green goop and Kai who gasped for air, she was soaked but otherwise unhurt. The goo coalesced into a human-esque form and flashed green leaving Jen behind, also soaked. She grabbed for her bag and pulled it open.

"They're dry!" She cried out in triumph. Kai laughed and held up her hand for a high five. Jen obliged and they both laughed as Wes shook his head.

"What happened?"

"Booby trap." Jen explained pulling out two books from her bag.