Kim Possible and all related characters are the property of Disney.

Doctor Who and all related characters are the property of the BBC.

This chapter features the Twelfth Doctor.

"I think we have it!" Wade announced. He was in the Denver UNIT base's main lab, and he was closing up the outer casing of a metal cube. "This is the new and improved version of the Doctor's old Zygon detector."

"I installed the memory core from the Time Lord prison I initially left Tolkran in," the Doctor added. "That's why it's bigger and much less portable. We're going to cobble together handheld units linked wirelessly to the main device."

"Are we sending him back to that prison?" asked the newcomer, Sergeant Pam Mazing.

"No," the Doctor replied. "I still think he needs community, not incarceration. My plan is to place him with some of the Zygons living on this planet."

"Good," Pam said. "That's good."

"All we have to do is turn the unit on, link up with the portable handheld units, and start the search," Wade told them.

"Then what?" Ron asked. "I mean, no offense to Pam, but we were expecting a whole strike team."

"No offense taken," Pam said. "I'd be more comfortable if even one of those jerks I had to serve with cared more about duty than kissing up to Place and Heath."

Kim looked around her. There was a Time Lord, a schoolteacher who had a lot more experience with aliens than Kim herself did, her tech genius, the only member of a UNIT strike team who wasn't more loyal to their commanders than to UNIT itself, and a bestselling author. A bestselling author who was also her ex-boyfriend.

Correction, one of her ex-boyfriends. The other one was in the brig with his fiancé. This was going to be difficult. A lot more difficult than she had previously thought.

"Okay, here's the sitch," Kim said, making sure she had everyone's attention. "I won't lie, we're so in over our heads here. My original plan went out the window before I even really made it. I'd wanted to have a way of flushing out Tolkran without putting Ron in any danger." She gave her former sidekick/boyfriend a sympathetic look. "Now, I can't do that. We may have to use your idea."

Ron nodded as he put his serious face on. "Booyah," he said.

"It's a last resort," Kim added. "So no going out there and taking unnecessary risks. Got it?"

"This is a capture mission only," the Doctor added. "Yes, Tolkran has done some vile things, but I'm operating under the assumption that he is a victim. Zygor was destroyed in the Time War, leaving him displaced on an alien planet in an alien time. I want to help Tolkran, not destroy him."

"Agreed," Kim said. "I so don't go in for wholesale slaughter. That having been said, we will defend ourselves. That's where you come in, Pam."

Pam smiled. "Got it, Kim."

"Okay, people, let's get this done," the Doctor said. "Wade and I will finish the handheld units. When that's done, we'll go find our shapeshifting friend. With any luck, we'll find him before he abducts anyone else."

Ron quirked an eyebrow and looked over at Kim. "When have we ever had that kind of luck?"

Kim chuckled. "In our dreams, I think."

While everyone else went about their work, Ron found a quiet spot so he could try to meditate. In this case, "try" was the operative word. Ron's mind was often chaotic, with random thoughts and ideas swirling through his consciousness like water surging through a whirlpool. That was great for a writer, not so great for someone trying to calm that chaos in order to meditate.

Ron sat in the lotus position, his eyes closed. He tried to rest his body and to let his mind relax. He tried to release those ideas and thoughts, he tried to calm his conflicted heart, but he couldn't. Ron opened his eyes and let out an annoyed grunt.

"Meditation was never easy for you," a voice said. The glowing image of Sensei shimmered into view. "The only time you are able to calm yourself, it seems, is when you are cooking."

"And this place already has a cooking staff who probably wouldn't let me near the kitchen." Ron stretched out his legs, allowing his knees to pop. There was a time when Sensei appearing out of nowhere would freak him out, but he was used to it now. Besides, he was already freaked out.

"What troubles you, Stoppable-san?"

"Everything," he said quietly.

"Could you, perhaps, elaborate?"

"The past has come back to haunt me, Sensei," Ron said. "Tolkran and Kim. A one-two punch of bad memories I thought I'd moved past. I mean…" he trailed off. "I don't know what I mean."

"How are you and Possible-san interacting?" Sensei asked.

"Okay, I guess," Ron replied. "I forgave her." Sensei smiled under his beard. "And I gave her some comfort when she finally forgave the jerk she left me for." Ron slumped. "We're starting to act like we used to. Like no time at all has gone by, and it's freaking me out!"

"I think I see your dilemma," Sensei told Ron. "When I spoke to Possible-san at Yamanouchi tonight, I could see that she still had feelings for you, just as you still have feelings for her."

"It's been eleven years since we broke up, Sensei," Ron protested. "Well, eleven years for me. It's been ten years for her. I tried my best to stop feeling things for her."

"The heart wants what it wants," Sensei pointed out. "We cannot control what we feel and for whom we feel it. If there is one thing I tried to teach you, it is that there are some things out of our control. That includes our emotions. No one is saying you and Possible-san should give yourselves a second chance. However, I think you should let yourself feel what you feel and not fight against it."

Sensei's expression softened. "I do not know what the future has in store for you. Once you fulfilled the prophecies you wrote with Toshimiru, my foreknowledge of your destiny came to an end."

"I kinda wish Toshimiru was here now," Ron admitted. "He gave good advice, and he knew how to tell you what you don't want to hear but in a way that you'd listen to him."

"Alas, that is a skill I do not possess."

"What am I supposed to do?" Ron asked.

"Who says you are supposed to do anything?" Sensei countered.

"I told Kim ten years ago that I still loved her and wished I didn't. I still feel that way." Ron took his glasses off and rubbed his eyes. "I just… I don't know, Sensei. I don't know what I'm supposed to do."

"I've been saying the same thing to myself today," a voice from the doorway said.

Sensei looked up and saw Kim. "I will take my leave. I think this is a conversation you should have without me." With that, Sensei vanished.

"Now what?" Ron asked as he put his glasses back on.

"I don't know," Kim said honestly. "You probably won't believe me, but I never stopped loving you. Even with what I did to you. I felt guilty through a lot of mine and Reed's relationship knowing that I still loved you."

Ron tried not to scowl, and mostly succeeded. "No guilt when you were seeing him behind my back?"

Kim let out a short, mirthless sigh. "There was nothing BUT guilt when I was doing that. My therapist could have made a fortune off my visits had they not been provided by UNIT free of charge." She sat on the floor directly across from Ron.

"We need to at least start to figure things out," she told him. "We have to get our heads in the game. This is a life or death sitch. Your life or death. It's bad enough I'm the girl who cheated on you and broke your heart. I don't want to be the one who gets you killed, too."

Ron rested his head against the wall. "It hasn't even been a year since Rita ditched me. I'm so not ready for another ride on the relationship train. And I'm sorry, Kim, but I still don't trust you."

Kim nodded. "I get it. It's hard to rebuild trust after it's been torn down and set on fire." She looked Ron in the eyes, in those expressive bronze orbs that she would just stare into when they were dating. She used to get lost in those eyes, especially since she could tell what Ron was feeling just from gazing into them.

Now, though, she couldn't read him. She'd lost her Ron to Kim dictionary, and her ability to just know when something was wrong or get an idea of what he was thinking or feeling. It took a lifetime to develop that ability to read him, and only a decade to lose it. This was worse than starting over. They would have to get to know each other all over again.

"Ten years is a long time," Kim said, almost to herself. "Neither one of us is the same person we were the last time we saw each other." Ron nodded in agreement. "I know this sitch has totally thrown you off. You probably thought I was out of your life for good." Again, he nodded. "I had, very reluctantly, accepted that only a couple of years ago. And it hurt. It really hurt. Not as bad as knowing that it was my fault, but it hurt so bad.

"I did blame you for a while," she admitted. "If only you had accepted that our relationship was doomed, then we'd still be friends. You would have understood that, even though I'd cheated on you and hurt you, it wasn't done out of malice. If only you'd stayed and talked to me instead of taking off without even saying goodbye, you would have seen things my way and we'd be fine." Kim shook her head. "It's taken years of therapy to figure out how wrong I was."

Kim was quiet for a few moments as she tried to organize her thoughts. "'I know what I did was awful. No, that's not right. Awful isn't nearly bad enough. Horrible? Monstrous? Abominable? Yeah, abominable. That works. I found the right word without sounding like I was reading from a thesaurus.

"'It was abominable. You didn't deserve that kind of heartbreak, and especially not from me. I forgot the promises we made to each other in front of our families, and I forgot what the words 'I love you' really meant. I did love you, just not enough to tell you what I was feeling, and not enough to be honest with you. I can never apologize enough for what I did'."

Ron was slack-jawed. "That was, word for word, what Monica Hoffs said to Derek in Fire From the Abyss!"

"I've almost completely memorized that book from how many times I've read it," Kim said. "I figured out that you'd wanted to hear something like that from me instead of the excuses I fed you when I broke things off with you."

"I don't even know where all that came from," Ron admitted. "I'd been up for two days straight, had been pounding Slurpsters like they were going out of style to keep my caffeine levels up, and the words just flowed out. It was like a dam broke, y'know? It wouldn't stop."

"I guess your subconscious knew what it was you really needed to hear, and let you write it instead," Kim told him. "I cried my eyes out when I read that. It was an emotional slap in the face. That was when I really started to figure out how badly I hurt you. I hate that book, needless to say, but I read it a couple times a year, just so I don't forget that lesson."

Kim's expression softened. "I can never apologize enough for for what I did." She took a breath, held it, then let it out. "In the TARDIS kitchen, you asked me what I wanted from you. It was the same question you asked me ten years ago. Back then, my answer was so selfish. It still is. I want you in my life again, even if we're just acquaintances. I'd love to pick up where we left off, but I know that's not possible. Too much time has passed, and there's been too much hurt. We don't really know each other anymore."

Kim stood up and held out her hand. Ron took it and she helped him to his feet. "I want to be your friend again, Ron Stoppable. I want to get to know you again. This time, I promise, I won't betray you."

"I'd like that too," Ron said.

"Good." Kim wiped her eyes. She hadn't realized that she'd been crying. "First thing's first, though. We have to live through this sitch."

"Yeah," Ron agreed. "We've got this. I've survived this kind of thing with the Doctor before, and against this particular Zygon. I'm old hat at this. I think letting Paige know I was alive and well was harder than this is gonna be. She was tweaked that it took me this long to call her."

"Paige?" Kim asked, confused.

"My agent. Paige Turner. She's could scare a Dalek if it got on her bad side. That's why she's such a good agent. She'll fight tooth and claw if she thinks I'm not getting my due."

"What did you tell her?"

"That a super secret law enforcement agency had me in protective custody."

Kim gave Ron a quasi-dirty look. "You didn't."

"I did," Ron said with a grin. "I just didn't say which one. I didn't even mention you by name. Besides, Paige knows about me being an ex-sidekick. She rolls with it."

"Okay," Kim said grudgingly. "I'm going to trust you on this. Now come on, let's see what our resident geniuses have come up with."

"We're all set up," Wade announced when Kim and Ron walked back into the lab.

The Doctor came over with several devices the size of smartphones. "And here are the handheld units. We'll network through the TARDIS instead of your system here, Kim. Since we'll be taking the TARDIS to wherever Tolkran is holed up, it makes more sense than hoping we'll get a signal from all the way here in Denver."

Kim nodded. "All right then, when you're ready, switch on. I want to know where Tolkran is."

The device itself was a cube the size of a shipping box and had several small switches on it. The Doctor flipped those switches, making the device hum. A large flatscreen monitor on the wall turned on. A map of Middleton appeared on the screen.

The image zoomed in on a section on the outskirts of town. The image went from above ground to the sewers. "Great," Kim deadpanned. "Wade, we'll need the industrial strength nose plugs."

"And the hazmat suits," Ron added.

"This is weird," Wade said. The image was now locked in on what looked like an ordinary metal door. "According to the sewer plans, that door shouldn't be there."

"Definitely odd," Kim agreed. "Could it be an addition that's not on the plans you have?"

"These plans are up to date," Wade told her. "That door shouldn't be there. That should be a solid wall, and there are no treatment or pump rooms in this stretch of sewer."

"Supervillain lair?" Ron asked.

"Maybe," was Wade's reply. "It's not one of Drakken's. He had to disclose all of his assets when he was pardoned."

"Besides," Kim added, "I so can't see Shego living in a sewer."

"Dementor?" Ron suggested.

"Maybe."

"Where is Tolkran in relation to this door, Wade?" the Doctor asked.

"He's right there." Wade pointed at the door. "He's either right there, or on the other side of it. I can't pin it down any closer." His computer pinged. "And now we've lost him. I don't get it. This device should have a nearly unlimited range!"

"Something may be masking his bio-signature," the Doctor surmised. "Give me Tolkran's last known coordinates and I'll program them into the TARDIS."

Kim looked from the Doctor to Wade. Then she turned her attention to Clara, Pam, and Ron. "Okay, people, here's the sitch. We have a hostile alien who is now on the other side of a phantom door. I have no clue what's waiting for us there."

"Sounds like another day at the office to me," Clara said.

"Clara's right, Kim," Pam said. "This is why we get the big paydays."

Kim snickered. "On a UNIT salary?"

Pam smiled. "The hazard pay almost makes it worth it."

Kim looked at Ron. "Are you sure you want to do this?"

"No," he replied honestly. "But we gotta do it."

"Right then," the Doctor said, "everyone into the TARDIS! We have a Zygon to find."

Next: The Other Side of the Door