Title: Full Moon Rising
Disclaimer: Any characters, concepts and names you recognise don't belong to me. The plot line was thought up by someone long ago, I'm sure, but for the purposes of this fic, it's mine
Rating: T
Notes/warnings: Set during the first and early second seasons of SGA. Spoilers in this chapter for 'Rising' only.

John isn't exactly human, and hiding it in the Pegasus galaxy isn't going to be the easiest thing in the world.

Chapter 1 - The Beginning
The first time it happened in the Pegasus galaxy, John Sheppard cursed his luck and managed to hide in his room until the end of the night. The next day, after waking naked on his bed, he went to the scientists and managed to persuade them that really, he was just interested in the different lunar cycle here on Atlantis.

The full moon came roughly every two Earth months, so he figured he had plenty of time to work out what to do next time. He'd hoped he wouldn't have to deal with it in another galaxy, but fate was apparently relentless.

The second time it happened was after the incident with the life-sucking bug, and so John had an excuse to be holed up in his quarters from the moment the moon rose to the moment it set. It was then that he discovered that Ancient technology responded to him just as much in his animal form as in his human one.

He spent the better part of the night turning the lights in his room on and off and pouncing at the resultant shadows.

The third time it happened was just after the storm, and his animal self wasn't quite separate enough from his human self to enable restraint, so for the first time in this shape he allowed his door to open, and he stealthily started on a patrol around the city.

Usually the lights automatically came on when he walked along the corridors, and it took some effort for John to remember to think 'off' at the lights all the time. After a while it became easier, and he was able to concentrate on exploring Atlantis in this form.

His tail flicking lazily, he padded through the places that were so familiar to him as a human. He was used to seeing things differently in this form, but Atlantis was a visual feast even without his enhanced eyesight. A part of him – the human part – was glad that he only had monochromatic vision. Colours would overwhelm him here. The sounds as well were incredible; his ears twitched with everything he could hear.

He moved silently through the city, pausing at closed doors to listen to the sounds of those sleeping within. He avoided the central tower entirely; self-preservation kicking in as well as the common sense of his human self. He marked his territory in moments wholly taken up by his animal mind, and scratched uselessly at some of the walls.

He missed trees.

He stalked shadows, pouncing playfully and enjoying the freedom. At the same time he was fully alert, waiting for the ambush that the human part of his was sure must be waiting.

He had wanted to be in this form earlier, during the storm, when his city had been threatened. It was so much easier to hunt, to kill, when he was like this.

At the thought of it he growled deep in his chest, and then before he could help it he let loose a shrieking roar, sounding for all intents and purposes like a screaming woman.

Lights went on; doors flew open and someone – several people, but he only really noticed one – stumbled into the corridor.

"What? What's going on?" the man asked. John's human mind disappeared into the animal's; he gave another shriek, turned and fled.

He woke in the morning to an insistent voice coming through his radio. He rubbed a hand across his eyes, adjusting quickly to the change in vision, and answered it.

"Sheppard here," he said roughly.

"Major! Where are you? You haven't been answering the radio," came Elizabeth Weir's voice. John grimaced and started pulling on clothes. "There was some sort of an incident last night, we couldn't get hold of you."

"I, uh, went for a run," John said unconvincingly. "Forgot my radio." He hooked the radio around his ear properly and started lacing his boots. "Sorry. What happened?"

"McKay…thinks he saw something, and several people heard screaming. Lieutenant Ford has searched the entire area, but…"

"Where was this?" John asked curtly. He pulled on his jacket and weapons before running a hand through his hair in a half-hearted attempt to tame it.

"Outside his lab." Elizabeth's tone had changed from worried to slightly amused. "Carson thinks it was most likely a hallucination, especially given that Rodney hasn't slept much since the storm. But several people heard a scream, so I'm concerned."

"I'll be there in ten," John promised, already leaving his room, and frantically trying to work out how to explain away what Rodney had seen last night.

"Good. Afterwards, come up to my office. I'd like a word."

"Sheppard out," John grimaced, lifting his hand to switch the radio off. He knew exactly what she wanted to talk about; the ranking military officer on Atlantis couldn't very well forget his radio without repercussions.

But it wasn't as if he could speak in his animal form, let alone fit the radio over his ear.

"For the hundredth time, yes, it was a scream! Like a woman screaming."

John heard Rodney before he saw him, and couldn't stop a smile from forming. He liked Rodney – and it had been no coincidence that it was Rodney's lab he had lurked outside the previous night.

Someone else said something quietly, and Rodney responded instantly.

"Yes, I'm sure I wasn't hallucinating! I'm telling you, I saw a great big animal!"

"Hi, Rodney," John drawled, turning a corner to be greeted with the sight of Rodney, Ford, Zelenka and several marines. "So what's all the fuss?"

"Sir," Ford said, with more feeling than John had thought possible. "Dr McKay was –"

"Where the hell have you been?" Rodney demanded. "I see a giant cat monster and you're nowhere around! You're supposed to protect us!"

"Have the scanners picked up anything?" John asked Ford, ignoring Rodney with practiced ease. The lieutenant shook his head. "What about this scream?"

"Several people heard it, sir, but we've thoroughly searched the area. There's nothing here," Ford offered. "It could have been a practical joke."

"Not a very funny one," Rodney muttered. John looked properly at him, noting the dark circles under his eyes and the bandage on his arm.

"Rodney, get some rest," he said gently. "The city will still be here in twelve hours." He held up a hand to forestall the complaints. "No. I will personally search for this…big cat, but only if you go and sleep."

"Well…I…suppose I could do with a nap," Rodney muttered. "But listen, wake me up as soon as you find anything."

"Yes, Rodney," John lied easily. "Go to bed." He nodded at one of the marines. "Make sure Dr McKay doesn't get sidetracked."

Ford hid a grin; John started the pointless search for the 'creature'. An hour later he entered Elizabeth's office.

"I know, I should've taken my radio with me," he said before she could speak. "It was dumb, I wasn't thinking." He smiled his most winning smile. "I'm sorry."

Elizabeth rolled her eyes, aware of his tricks after several months in Atlantis. "Of course you are. John, if there had been a real emergency –"

"I know." John folded his arms, expression grim. "Trust me, after the last few days, I know." He draped himself over the seat in front of her desk. "Look…it won't happen again."

"See that it doesn't," Elizabeth said sternly. "Anything new on this…creature of Rodney's?"

"No," John shrugged. "To be honest, I think it was a mixture of him being exhausted and somebody playing a practical joke with that scream. Everyone's jumpy after what happened…it's only to be expected. I've sent Rodney to bed, hopefully he'll actually get some sleep."

"And he actually went?" Elizabeth said, eyebrows lifting. "Wow. How did you manage that one?"

"Not sure, actually," John grinned. "I think he was really, really tired." He narrowed his eyes slightly. "He's not the only one. Have you even been to bed since the storm?" She shifted slightly. "Uh huh. So you're fine with ordering me off-duty, making sure Carson gets some time to sleep and checking that the science team aren't driven insane by Rodney…but you won't rest yourself?"

"It's been busy," Elizabeth tried to excuse herself. "There's been a lot of repairs to oversee…"

"Elizabeth." John leaned forwards and waited until she was looking at him. "Seriously. Take the day off. There's nothing urgent to be done. There's no teams off-world, there's nothing you need to be doing."

"I can't just –"

"I can get Carson up here and get him to back me up," John threatened lightly. "He'll probably make you go into the infirmary."

"You've convinced me," Elizabeth said with a faint smile. "But you'll contact me if anything happens?"

"Of course," John nodded, standing up. "But I don't want to hear you on the radio unless I'm contacting you, okay?"

"Okay," Elizabeth conceded.

John watched her go with a faint smile. Mistake covered, he concluded.

To be continued.