AN: This is my first attempt at a crossover. This idea wormed its way into my brain and wouldn't let go. For those that don't know, the actor that plays Kevin Lynch (Nicholas Brendon) used to play a sidekick (Xander Harris) on Buffy the Vampire Slayer. That is where this comes from. Willow was Xander's best friend and an uber-powerful witch. She was also a computer nerd, which I think is funny and maybe a little too coincidental.

I own nothing…not Criminal Minds or Buffy the Vampire Slayer. But I would give my left arm to own a piece of Derek…or Hotch…or Angel…

Penelope was thirty minutes late for work. She hated being late. At least this time she had a good excuse; she was going crazy. As she hurried through the bullpen, she caught Morgan's eye. She beckoned with her head for him to join her as she strode directly towards Hotch's office. She was grateful that there was no case to distract them with. When she got to his door, she knocked and waited for his reply. When he called out for her to come in, she took a deep breath, opened the door and stepped in with Derek right behind her.

"Garcia, so glad you decided to join us today." Hotch said slightly sarcastically.

"I am so sorry sir. The reason I am late is also part of the reason I need to ask to take today off." Penelope told him.

When Hotch's look told her to continue she said, "Sir, I need to see a doctor. I think I am losing my mind. There is definitely something wrong with me."

"Baby Girl, what are you talking about?" Derek asked before Hotch had the chance to say anything.

"I don't know if I am having delusions or hallucinations or what it is, but it is really starting to give me the wiggins. I set something down, turn around and when I look back, the item is across the room. Or I'm sitting still somewhere and something that is steady and sturdy on a surface will just fall to the ground for no reason. This morning was the worst. I have lived in that same apartment building for years, I know my way to the front door. Today I couldn't find it. I got lost in what seemed like a maze of hallways. That's why I'm late, I got lost in my own building. I think I need to see a doctor."

Both Hotch and Derek were looking at her with concern. Hotch said, "Definitely Penelope. Take the day off and go see someone. Derek, go with her. We don't have any pressing concerns. If something comes up, I will give you a call. Let me know what happens."

They both nodded and left the office to head to the hospital. As they made their way through the bullpen Penelope tripped and would have gone face first onto the floor if Derek hadn't caught her.

"Whoa, Baby Girl, you ok?" Derek asked softly.

"See, this is exactly what I am talking about. There was something suddenly in front of me. I felt my shoes hit it and my legs brush something solid before you grabbed me, but there is nothing there. I'm scared Derek, what if I really am going crazy? What if it's like a tumor or something?"

Before she could go into full blown panic stage Derek shushed her with his fingers over her lips. "It will be ok, Mama. No jumping to conclusions until we have seen a doctor. Come on, let's go and get this behind us."

He wrapped his arm around her waist to keep her from tripping over other invisible objects and guided her out to his car.

7 hours later…

"Nothing? I cannot believe they found nothing! If I am seeing things and falling over things that aren't there, there should be something wrong with me!"

Derek chuckled, only Pen would be upset that the doctor didn't find a tumor.

"Sshh, Mama they still have to test the blood work. Who knows, maybe you're just anemic and you're hallucinating because you need me to cook you a big, juicy steak." Derek told her with a wink.

"Mmm, food does sound good Hot Stuff. I skipped breakfast because the eggs I had sat on the counter kept moving and I couldn't hold on to them long enough to cook them and lunch was when I was waiting on a CT scan. How about you make the food while I shower the hospital off of me." She replied saucily.

Derek wrapped his arms around her waist. "How about I do my own exam? You know, just to make you feel better? I will strip you down and examine every lovely inch, and I will bet you I won't find any imperfections."

Penelope blushed, didn't matter how comfortable they were with each other; his compliments always made her cheeks red. "You know how to make me ok…with anything. I love you so much for that." She gave him a quick peck on his nose and then dis-entangled herself from his arms. "But shower and food first, I want to be relaxed and ready for bed. Because when you are done with me I won't have the strength to get up. "

Derek snickered as he headed for the kitchen and she went to shower. "You're right Baby Girl; you won't even be able to pick your head up."

"I'm holding you to that, Handsome," Penelope said as she entered the bedroom. A movement caught her eye, and she screamed when she saw someone in their bedroom.

She heard Derek yell her name and knew he was coming but she wasn't really scared, which was weird but the person didn't frighten her. She had just been startled that someone was there. It was a woman, she was pretty, she looked normal and she was standing in Derek's bedroom. Didn't take a genius to figure out why she was there. Pen knew then that they would have to find somewhere else to move in to together; she would not move into a house where Derek's exes could just show up.

Neither woman had said anything by the time Derek got to the bedroom door with his gun drawn. He stepped in front of Penelope and asked the woman, "Who are you? How did you get in here?"

Penelope's head jerked as she turned to look at him, "What? You don't know who this is? She isn't…ya know…a friend?"

"Only redhead I've ever gone for before was you sweetness" Morgan told her, not taking his eyes off the woman. She was staring at Penelope and it unnerved Derek. "I'm gonna ask you again. Who are you?"

Never taking her eyes off Penelope the woman said "You should put the gun away. It won't do you any good."

"That's not going to happen until I know why you are here." Derek told her.

Penelope was lost in thought; she was envy-ing the color of the woman's hair. It was a beautiful deep red color. If she ever went red again, she was going for that. She blinked and the woman was gone.

"What the…?" Derek said, "Where the hell did she go?"

"I am so happy you are here right now. I really would have thought I was crazy if I had seen that alone." Penelope told him.

She turned around and screeched when she saw the woman standing in the bedroom doorway. Derek turned too and pushed Pen behind him with his left hand.

"You really should put the gun up. Unless you want me to take it from you?" The woman said calmly.

Before she could stop herself, Penelope snorted, "I'd like to see you try."

The woman snapped her fingers and in the next instant Derek's gun was out of his hands and in the woman's.

"Whoa, how in the hell did you do that?" Penelope asked, "And why are you here?"

The woman snapped her fingers again and disappeared once more. They heard her voice call for them to come into the living room.

"I didn't feel like standing anymore," the woman replied as she sat in Derek's recliner. "You should get comfortable. My name is Willow; you caused a friend of mine a lot of pain and I would like to discuss that."

She waited until Penelope sat on the couch and Derek sat on the armrest next to her, as far away from their guest as possible. Not that space would do them much good apparently.

"May I ask who your friend is?" Pen said softly. She figured if she stayed with the 'no sudden movements and no loud noises' method she wouldn't spook Willow. That was the absolute worst thing that she could do. Penelope had an idea of what Willow was and knew there was nothing they could do until Willow was done with them.

Willow snapped her fingers and there was another person in the room. Kevin Lynch was standing there in boxers and a baggy t-shirt. He looked around and when he saw Willow, Penelope and Derek all staring at him, let out an exaggerated sigh, "Will, I told you to leave her alone. What are you doing?"

"You're right; she is shacked up with another guy. I just wanted to have a little chat with her, after a few days of getting a taste of what her life could be like." Willow told him with an innocent look on her face.

"That was all you?" Pen asked relieved, shocked and angered all at the same time. "You were moving things and knocking things off and rearranging my hallways?"

Kevin turned to Willow with his mouth open, "Willow, you shouldn't have done that. Dammit, Will." He ran his hand over his head and turned to face his misinformed friend. "Look, I may have embellished a little when I was telling you what happened…."

When he trailed off Penelope knew exactly what had happened. She jumped off the couch and stood in front of Lynch. "You told her I cheated on you, didn't you? You told her I broke your heart for another man? I think you need to set her straight right here and now. What are you thinking, lying to a witch?"

"Witch?" Derek asked, coming to stand behind Penelope.

"How did you know she was a witch?" Kevin asked.

"Because I have eyes Kevin. She disappeared in front of us and took Derek's gun out of his hand without moving a muscle. I don't think she's a magician so that leaves witch."

A soft voice from behind them stopped them from launching into a full-blown argument. "I would really like to know what you mean by 'embellished', Xander."

"Xander?" Penelope asked.

"Short for Alexander Harris, which is my real name. Willow, Penny didn't cheat on me, I cheated on her. That's why she left. She didn't get with Derek until after we broke up. I just didn't want to tell you that I finally was with a normal girl and I still screwed it up." Kevin/Xander looked sheepishly between Willow and Garcia.

Willow gracefully stood up from the chair and strolled over to her old friend. She raised her hand and smacked him upside the head. "Xander, I have really felt bad these last few days messing with her. Penelope is a decent person and I would love to learn code from her. She could teach me a lot. But I've probably screwed up that chance because I thought I was sticking up for you."

Rubbing his head he replied, "Well, no one asked you to do that Will. In fact, I specifically asked you NOT to do what you did."

"Willow, I'm sure we can work something out," Penelope interjected. "Actually I think an exchange of information could be the start of a beautiful friendship. Can witchcraft be learned?"

"Baby Girl, whoa, I really don't think that's a good idea." Derek told her.

"She's got potential Derek," Willow said to him. "It would be very easy for me to teach you."

Now it was Kevin/Xander's turn to intercede. "Will, are you sure? Are you allowed?"

"Xander, if you don't shut your mouth I will tell them about all your girlfriends in high school. Do you want that?" When he shook his head she continued, "Giles certified me 5 years ago to teach. I think that's the best review I can get."

"I think you should tell me about his past girlfriends anyway, ya know, since he put all of us through this." Penelope snickered when Kevin's face paled. "How bad can it be Kevin? We all have things in our past we wouldn't repeat. I would also like to know what I am normal compared to."

"You're the first human girlfriend he's had." Willow told her

"Ok, can I go home now if this is going to turn into girl's chat? Or at least have some pants?" Kevin asked, trying to distract from embarrassing stories.

They both ignored him. Derek shrugged his shoulders at him. He didn't really care about Kevin's love life until Willow made the human remark. Now he was all ears.

"He had sex with a teacher that turned out to be a giant praying mantis. We barely managed to save him from that." Willow said, already in the friend zone with Pen.

"Praying Mantis? Really? We're supposed to believe that?" Derek asked with disdain evident in his voice.

"It's true man. The things that go bump in the night are real. Vampires, werewolves…and every mythical beast in between. They are all real and in my previous life, and Willow's current one, we fought them on a regular basis. But then what would you expect living on the Hellmouth. " Kevin told him, finally giving up on the idea of pants and grabbing a blanket off the couch and wrapping it around his waist.

"Hellmouth? This has got to be just some elaborate prank." Derek said skeptically. "You can't really expect us to believe that Vampires are real and are out their sparkling in the sunlight and we just don't see them."

"Hush, Scully. I wanna hear the story." Penelope admonished Derek. She smiled at him when he mouthed 'Scully?'

"Derek, Penelope, please stand behind me. I am going to give Derek here a bit of proof." When they had both moved behind her, Willow closed her eyes for a moment and then snapped her fingers. They now had a fifth person in the room. She was a blonde bombshell built like a brick shithouse.

"Xander! Long time no see…I can tell your fashion sense has suffered with me not being around. Why are you wearing a blanket? Will, why did you bring me here and who are your friends?" The blonde asked, not fazed at all by suddenly being somewhere different.

"Buffy, meet Penelope and Derek. Penelope was Xander's ex-girlfriend. He told me that she cheated on him and moved in with another guy, when in reality he cheated on her. I have been messing with her the last few days and now I am trying to fix things. I was going to give them a demonstration on how real certain things are and while Xand and I could definitely handle a vamp on our own; I wanted them to see you in action." Willow told Buffy, who was shaking her head at Xander.

"Xander, you and I are going to talk later. For now, Will let's get this show on the road." Buffy said.

"My thoughts exactly." The redhead snapped her fingers and all five were standing in a cemetery. Derek and Penelope looked around trying to get their bearings. Pen started laughing when she saw Willow hadn't let Kevin bring his blanket.

"Ok guys, Buffy is what we call a vampire slayer. One girl born with the power to fight evil and yada yada. Just stay behind us and watch and learn." Willow said and then closed her eyes.

Before she could snap her fingers, Buffy said, "Hey Will, cut me some slack and give me a stake. I wasn't exactly prepared for battle when you summoned me."

Willow snapped her fingers and there was a stake in Buffy's right hand and the scariest looking man Penelope had ever seen standing in front of her.

"What the hell is wrong with his face?" Derek asked.

"That's a vampire, Morgan. That's what they look like," Kevin told him. "This is how we spent our high school years."

The vampire lunged towards the group but was stopped as Buffy's foot connected with his jaw. As Pen and Derek watch amazed, the little blonde dynamo kicked the vampire's ass all over the graveyard. Penelope wasn't even surprised when he turned to dust after Buffy put the stake through his heart.

"Wow, you can do that Kevin?" Penelope asked, she had already believed them, but seeing it was uber cool.

Hearing her tone of slight admiration, Derek felt a tug to his male pride and said, "I bet I could do that." When Kevin laughed at him he wanted to do it all the more. "Morgan, vampires are a lot stronger than you think. Buffy has super strength which is how she makes it look so easy."

"Kevin, if you can do it, I know I can." Derek told him. "Besides, Buffy is still here and can help. This could be a helpful lesson in the future and I would rather learn it now with backup."

Buffy and Willow exchanged a look, Buffy shrugged and Willow nodded. Willow grabbed Penelope's arm and pulled her a little closer and then snapped her fingers once again. Penelope watched, eyes wide, as her man circled the vampire. She had seen Derek spar with others in the gym but she had never seen him take on anyone for real. This was very exciting to her and it also made her just the slightest bit turned on.

It took a moment for Derek to become accustomed to the superior strength of the vampire. He fell back on his training and used the vamp's strength against him. He got knocked around more than Buffy had, but he was holding his own. He jumped up and landed a solid round-house kick to the vampire's head and caught the stake that Buffy tossed him and plunged it into the vampire's heart. Just like before it turned to ash and left Derek standing there panting.

"Dammit, he even does that better than me!" Kevin exclaimed, childishly.

The slightest bit of Penelope that was turned on bloomed into her entire body. She really wanted to be alone with Derek and she wanted that right now. She whispered to Willow who nodded and snapped her fingers one last time.

Derek and Penelope were back in Derek's living room and everyone else was gone.

"Where'd they go?" Derek asked, still holding the stake.

"I told Willow to hit me up later and asked if she would send us home. I couldn't wait any longer to have my hot chocolate God alone." Penelope started moving towards him, swaying her hips and licking her lips.

"Ah, Baby Girl, did I turn you on?" Derek asked her with that smug, self-satisfied smile that he wore when he knew she wanted to jump his bones.

"Oh yea, Hot Stuff and I'm gonna show you a good evening, and then you can help me figure out what the hell we are gonna tell Hotch tomorrow, cause it ain't gonna be the truth. "

Derek threw his head back and laughed. Then Penelope was in his arms and was stealing his breath with her hot little kisses. He had a vague thought of gratitude towards Kevin. He never would have thought that Kevin cheating and lying would have turned out so well.