Author's Note: This one is for the Rivalryislove, first five lines ficathon over at livejouranl. Just a little one shot, set a couple years in the future, I'm picturing Casey and Derek as 18 or 19 in this one, but it doesn't really matter.

There are more lines I have for this ficathon, but this first line produced the first plot bunny.

Just as a warning, the prompt line DOES include a naked Derek. Oh and Mal(if you get this alert) there's word I included just for you.

Disclaimer: Still not mine.

"Um, Derek...not to pry or anything, but, er...why exactly...are you naked?"

Derek froze in his tracks at the sound of Jason's voice. How was he going to get out of this one? How to you explain to your mother's new boyfriend, why exactly it is you're walking down the halls of his mountain condo, naked at three am? His mind ran through possible explanations as his hand clenched tightly around the bag inside it so Jason wouldn't see it.

He turned around slowly, trying not to let his panic show on his face. Jason wasn't a bad guy, considering he was about 10 years younger than his mother, and was a professional... something involving math that Derek didn't really understand. He, Edwin, Marti, Lizzie and Casey had been invited to spend a four-day weekend up in his little mountain cabin. Jason had been great, even taking time to teach Marti to ski- but Derek was still pretty sure he couldn't tell him the truth about what he was doing naked in the hall at three am.

"Just up to the bathroom, I um- sleep naked," Derek lied, grinning sheepishly hoping Jason bought it.

"Its a little cold for that isn't it?" Jason asked, arching an eyebrow in disbelief and gesturing out the window to the snow covered mountains.

"A little," Derek said with a shrug, "but its how I'm comfortable," he said, smirking.

"Ooook, but why didn't you put a robe on to walk to the bathroom?" Jason asked.

"Its three am, I didn't think I would run into anyone." Derek said, "and like I said, I'm comfortable this way,"

"To each their own," Jason replied, still looking amused. He started to turn back towards the master bedroom, and Derek started to breath a sigh of relief, but Jason stopped suddenly, as though a thought had just occurred to him.

"Isn't that Casey's room you're heading towards?" Jason asked look puzzled again.

"No, its the bigger room," Derek said, rolling is eyes for effect, "I couldn't let her keep it all weekend, a man needs his space,"

"So you kicked her out?' Jason asked

"No, not exactly," Derek said, "we just- traded," Jason leveled him a long look,

"Something isn't right here," he said, "but its three am, so I'm just going to let it go," He said, shaking his head and turning around.

"Goodnight," Derek called.

"Whatever," Jason said, "Good night Derek,"

Derek breathed a sigh of relief as the door shut, "finally," he hissed under his breath, opening the door to the large guest room.

"Where have you been?" Casey asked as he shut the door, " I thought you were just going to your room for a second?"

"I tried," Derek said, "Jason stopped me in the hall," he said sitting down on the edge of the bed.

"Jason?" Casey asked, sitting up in alarm, "but you're...you're... naked!" she whisper shouted.

'Yeah, he noticed that," Derek said, smiling wryly.

"So what did you tell him?" Casey asked.

"Oh you know, I just told him I'd been having a nice romp with you, he understood," Derek said, smirking.

"Derek!" Casey shrieked, smacking his shoulder.

"Ok, so I told him I sleep naked," Derek said, grinning.

"And he bought it?" Casey asked.

"I think he was too tired to care," Derek shrugged.

"But... we're not caught?" Casey asked.

" I think we're safe," Derek said, leaning down to kiss her.

"What did you leave for anyway?" Casey asked. Derek grinned and opened his hand to reveal a bag of candy watermelon slices, Casey's favorite.

"I bought them for you at the lodge earlier," he said, "I know how hungry you get in the middle of the night," he smirked and placed the bag in her hand, "post-romp that is," he finished. She giggled.

"Thank you," she said, leaning in to kiss him, "I didn't see these in the lodge," she said, taking one of the bag and eating it.

"You were busy trying to stop Edwin from buying that ax remember?" He asked.

"He could have been hurt!" Casey said looking pouty, "I still wished you had backed me up."

"I was busy buying you gifts. Don't complain." He said.

"Always an excuse," she said, but she was smiling.

"Always a complaint," he fired back.

"Can't let you get away with too much," She said,

"I'm pretty sure there's no danger of that." He replied, leaning back against the headboard and helping himself to one of her candies.

"Are you calling me difficult?" she asked.

"Yes," he said.

"Hey!" She said, smacking him again.

"But I like you that way," he said, leaning over to kiss her, a kiss that lasted them until the next morning, when Derek finally put some clothes on.