Here is my entry for the CSIFO JAN/FEB, 2012 Fanfiction Challenge.

These were the requirements:

1) Sara receiving a teddy (lace negligee) from someone. (Valentine's Day is coming up!)

2) Someone has to say, "I know what you are up to!"

3) You must include a mystery of some sort.

My thanks to my beta Dr. Temperance Brennan for her patience and for correcting my mistakes.

Summary: After his apartment floods, Greg goes to live with Nick. A potentially difficult situation only grows worse when Greg decides to bring Mortimer along. Also, Catherine's curiosity about Grissom and Sara grows.

Disclaimer: The characters of CSI do not belong to me.

MORTIMER: PART I

Greg's apartment flooded and was told that it would take a month to repair. Resignedly, he accepted that he needed to find a place to stay. After telling his coworkers of his predicament, Nick offered to let Greg stay with him. Greg immediately accepted the offer before Nick had a chance to change his mind.

Deep inside, Nick feared that he may have been making a huge mistake, but he had given Greg his word.

Saturday afternoon, Greg parked in front of Nick's house, his car overloaded with junk. "I couldn't leave this stuff there getting wet," Greg apologized, "but if you want I could keep it in the car or - "

Nick laughed at Greg's desperate tone and the puppy dog look upon his face. "Don't worry about it, man. Let's clear your car out, all right?" Greg agreed, excited to be staying with a friend. As they started to unload the car, Nick picked up a kennel and heard a noise from within. "Hey, Greg, what's in here?" He asked. Greg snatched the kennel out of Nick's hands.

"Hey! Don't swing that! Mortimer will get dizzy!"

"Mortimer?"

"My pet."

"Woah Greg, you didn't say anything about bringing a pet. What is it, a hamster?"

"No, a mouse."

"Mouse?" Nick asked in a tight voice.

"Yeah. If Grissom can have a tarantula, why can't I have a mouse?" Nick walked away, shaking his head.

"Don't tell me you're afraid of a mouse!" Greg called after him. Nick turned around to respond.

"I'm not...afraid of them. It's just...when I was a kid this huge field mouse attacked me and now...I just don't like mice, okay?"

"Mortimer's only a laboratory mouse. He won't "attack" you."

"Doesn't matter. He's a mouse. I don't like any mice, Greg!"

"Okay, I promise to keep him away from you!" Nick sighed and moved back towards the car.

"What's this?" He asked, pointing at a bundle in the backseat.

"My blanket and pillow."

"I told you, you didn't have to bring anything like that."

"I know, but I can't sleep without them."

"Aw, did you bring your teddy bear, too?" Nick asked teasingly.

"No, I forgot." Greg replied as they walked towards the house together, Greg carrying Mortimer and Nick carrying a box of clothes. Nick stopped in his tracks.

"I was joking, man."

"I know." Greg said unconvincingly.

One night that week Greg had a shift off while Nick had worked a particularly difficult one. He came home at dawn, eager to take a shower and fall into bed. As he reached his front door, a deafening sound pounded into his ears. 'What the hell is that? If Greg was having a party, the house wouldn't be dark.'

He entered the house and didn't see anybody. He walked toward the guest room. The noise loud enough to wake the dead was coming from there. He opened the door and saw Greg's back to him as Greg moved with the music. Nick called out to him several times without result. He then turned off the stereo. Greg spun around. "What the he - " He started, but changed it to, "Hey Nick. How was work?"

Nick shook his head. "Have you seen the clock, Greg?"

"I just got back from the club now!"

"

Hey, man, I get it. It's your day off; you want to take advantage of it. But when I get home, I need to be able to rest. Which means it has to be quiet, all right?"

"Right. Sorry, Nick."

"Nah, it's fine. Can't believe the neighbors haven't called to complain, though."

"Well, I didn't hear the phone ring." Greg said with his most angelic face.

"Of course not. How could you have listening to music that can be heard two blocks away?" Nick exaggerated.

Another time, Nick and Greg worked the same shift. When they got home, Nick went into the kitchen for a drink and Greg went to his room. Soon after, Greg heard the sound of glass shattering and his name being shouted. He ran into the kitchen and saw Nick cleaning up the broken glass with a broom and dustpan. "What happened?" Greg asked.

"What happened is that damn mouse was inside the glass I was going to use!" Nick replied.

"So that's where he's been!" Greg laughed. "Did you see where he went?"

"It ran towards the stove."

"Poor thing! It must have been scared!" Greg said, getting on all fours.

"It got scared? What about me, Greg?"

"I thought you said you weren't afraid of him."

"I'm not! But you're more worried about some rat than me. It's not a nice pet like a cat or a dog, Greg."

Greg had retrieved Mortimer and whispered to him: "It's okay, Mortimer. Uncle Nick doesn't mean it."

"Wanna bet? If I find that thing running about the house again, I'm not going to hesitate to hit him with a broom!" Greg frowned at this and held his pet closer.

"How'd it get out of its cage, anyway?"

"I guess I must have left the door unlocked."

"Wait a minute...you weren't surprised when I told you what happened. Has he gotten out before?"

"Several times. And he always goes to the kitchen."

"Yeah, well, he's going straight to the neighbor's cat if he comes in here again."

One day, wanting to please his friend, Greg decided to make waffles. After he got back from his shift, he set the table and went to work preparing his grandmother's recipe. Unfortunately, the cooking didn't go exactly as planned.

Nick left the bathroom whistling and when he walked into the kitchen, all he said was: "What the fuck!"

"Calm down, Nick. I'll clean it all up." The kitchen was a disaster. In a bowl lay a goopy, doughy mass. The stove was filthy, the sink piled with dirty utensils. The waffle maker sat on the counter, burnt pieces of waffle sticking to it. Worst of all, water covered every surface of the room.

Nick mentally counted until ten and said as calmly as possible: "Greg, why does it look like a bomb went off in my kitchen?"

"I was trying to make waffles and they burned. The smoke made the sprinklers go off and ...Who puts sprinklers in a kitchen anyway?"

"Me! So idiot guests don't set my house on fire!" Greg lowered his head at the criticism and went sadly to his room. Nick looked around at his mess of a kitchen, not knowing what to do first. He felt bad for what he had said to Greg.

After all, it had been an accident; it could have happened to anyone. His guilt compelled him to go and apologize to his friend. "I'm sorry, man. I overreacted."

"You're tired of me being here. You hate Mortimer and all I've done is annoy you. I'm sorry, I'll find someplace else to stay." Greg replied.

PART II

That night, Nick and Greg went to the lab together, but didn't speak to each other.

In the locker room, Warrick asked Nick, "What's up? Problems with Mortimer again?"

"Nah, it's his owner that's bothering me." Nick replied.

Grissom walked in and asked, "Who's Mortimer?"

"Greg's pet mouse. Been driving Nick crazy." Warrick answered with a teasing smile to Nick.

Grissom straightened his glasses, put on a professorial air and told his subordinates, "You know Mickey Mouse was originally named Mortimer, but Walt Disney's wife Lillian thought the name was too formal, so he changed it."

"How do you know these things, boss? Warrick asked, flabbergasted by the amount of information retained by his supervisor.

"I read a lot and always ask questions. Never stop asking questions, boys. It's the best way to learn." Grissom explained.

"So, Griss, since you know everything, mind giving me some advice?" Nick asked. Grissom raised his eyebrow and waited patiently for Nick to continue. "You know Greg's been staying at my place, right?" Grissom nodded. "Well we got into a fight and I may have said some things I didn't mean...Anyway, I tried to apologize, but I think he's still upset."

"Nick, once our thoughts are spoken aloud, there's no getting them back. Unfortunately, apologizing for them often doesn't take away the pain they cause."

"So what am I supposed to do?"

"You wait, Nicky. That's all you can do. I don't have any better solution than that." Grissom left Nick in a thoughtful state and as he walked out he nearly bumped into Catherine, who was on her way in.

"Did you guys see that? It's like he has his head in the clouds."

"Grissom?" Warrick asked.

"Yes, Grissom! He hasn't been himself lately. You haven't noticed?"

"I'm sure he's fine, Cat. He always has a lot on his mind."

"Yeah, but he hasn't always had that goofy grin on his face. And there are other changes." Catherine insisted. "Nick agrees with me!"

"Sorry, but what do I agree with?" Nick asked, who until then had not participated in the conversation.

"I was telling you the other day how Grissom's lost weight, shaved, is dressing better. You said there's definitely something up with him." Catherine reminded Nick.

Nick smiled and shook his head. He had more pressing concerns than Grissom's appearance and Catherine's curiosity. Tireless, Catherine attempted to convince Warrick that she was right, but was silenced by Sara entering the locker room. Sara greeted them quickly, grabbed a couple of items from her locker, and walked out.

"Sara's been off, too." Catherine said, making a mental note to keep an eye on her female coworker.

"Cath, if there is something up with Grissom, and I'm not saying there is, you think there might be a reason he doesn't want us to know?" Warrick asked.

For a moment Catherine was speechless, but she soon recovered. "No. Grissom shouldn't keep anything from us. We're a team, Warrick." Warrick shook his head; Catherine was not to be dissuaded.

Sara took long strides in the hallways and soon arrived at Grissom's office. He was sitting behind his desk, absorbed in a book. Yet he someone sensed Sara's arrival and looked up at her with a smile. "Close the door and the shades, please." He asked her. Confused but willing to oblige, Sara did what he asked.

He stood up, pulled her to him, and sought out her lips for a passionate kiss. When they pulled apart, Sara said, "We have to be careful. People are getting suspicious."

"Who?" Grissom asked.

"Catherine, mainly. She thinks you've been acting differently."

"Don't worry about that. Catherine can be a bit...dramatic, at times." He smiled and tried to kiss her again.

Sara pulled away. "We may not have to worry about Catherine, but what about Ecklie? We shouldn't be so careless."

"Sara, the door is closed. The lights are off. Nobody has any idea we're in here." He tried to console her.

"Still, let's not get cocky, all right? Anyway, I didn't come here for...that."

"Why are you here, then?"

"I wanted to thank you for the...gift you left under my pillow, a lace negligee."

"So you like it."

"Yes. I'll wear it for you today." She spoke softly, her husky voice seducing him.

"It seems my gift for you may turn out to be more of a gift for me."

"Isn't that the point of lingerie?" She asked with a giggle. Sara turned to leave, needing to get away from him before she got too hot.

When Sara opened the door, she found Catherine eavesdropping. "I knew it!"Catherine exclaimed. "I knew you were together!" Sara looked at Grissom, wide-eyed with shock and anxiety. He gave her a soft smile, indicating that he would handle the situation. She smiled back and walked away.

"I know what you are up to!"

"Quiet, Catherine." Grissom admonished. "Do you want the whole lab to know?" He pulled her inside his office. He sighed. "Yes, Sara and I have been living together for a while now."

"And you love her?" Catherine pressed.

"Yes."

"Then why not tell us, Griss? I thought we were your friends."

"You are. We just can't risk Ecklie finding out."

"You can't think that any of us would tell him."

"No, of course not, it's just...some things are private, all right?"

"All right. Don't worry, Griss. You can trust me." Catherine "locked" her mouth and left his office.

PART III

Catherine endured a few days of silence, but when she couldn't keep the secret any longer, she told Warrick. Of course, Warrick had to tell Nick, who naturally passed it on to Greg, who thankfully had no one to tell but Mortimer. Thus, the "secret" of Grissom and Sara's relationship was soon known by all of their friends.

As for Nick and Greg, they continued to discover that despite being close friends, they didn't make very good roommates. So, the night before Greg and Mortimer were set to leave, Greg bought a bottle of champagne to celebrate. Yet Nick didn't look as happy as Greg had expected.

"What's wrong, Nick? I thought you'd be thrilled to be rid of us."

"Yeah, well, in a way I am, but at the same time I guess it'll be...lonely now, without you here." Greg smiled.

"All right, let's make this a toast to...friendship, instead." Greg proposed. Nick agreed.

The next afternoon, Nick helped Greg load his belongings back into his car. Before Greg left, he said, "Thank you so much for letting me and Mortimer stay with you. I know it wasn't easy, but I really appreciate it. You're a good friend, Nick."

Nick hugged his friend and said, "You're welcome, Greg. Sorry I wasn't always the best host." Both men laughed.

Greg started the engine and drove away. At the first stoplight, he noticed that no sound was coming from Mortimer's cage. He looked down and found that the door was open. He pulled over and began searching the car for his pet.

Back at Nick's house, a glass shattered in the kitchen. "Mortimer? That you?" Nick called. "I know what you're up to. Come here...come to Uncle Nick..."

THE END