BtVS by Whedon and Mutant Enemy. Short tales written for Nerdgirl's "Were-Animals Xander didn't get bitten by" at Twisting the Hellmouth.
Dawn pulled up to the Magic Box and rushed in, screaming about Xander going into convulsions.
Buffy dropped the book of prophecies she was holding and ran out the door, using her Slayer strength to help Xander out of the backseat of the car.
Unnoticed, a stray gust of wind blew the book to a certain page that gave insanely detailed information of what was happening at that moment.
Unfortunately, Xander and Buffy's return trip through the door created another gust of wind which turned the pages to a mistranscribed recipe for Jell-O.
Anya rushed to Xander and helped hold him down, while a quick-thinking Giles held his jaws apart and laid a broom handle between his teeth. "That should keep him from biting through his tongue," Giles said as he turned to the telephone... Only to hear wood splintering.
By the time Giles turned around again, the painful transformation was complete.
"I told him he should have gone to the hospital, but does anyone listen to me?" Dawn asked, annoyed and worried.
"It was just a nip, no stitches needed. How was I supposed to know it was hungry for more than just dried kiwis?" Xander grimaced, spitting the shattered wood out of his mouth.
Dawn waved her arms with emphasis. "Hello, squirrels are diurnal. Nighttime squirrels are bad - unless they have wings!"
"So, you're sane, right?" Buffy asked, twirling a stake in her hand. "No need for slayage or restraints, right? Wait, does silver work on weresquirrels?"
"No, we need the antlers of the famed Bullwinkle tribe," Giles said, sarcastically. "What? Despite what you may think I'm not a bloody encyclopedia. Right now..." he trailed off, longing for the liquor stashed behind the counter, but unwilling to put his friends at greater risk. "We need to consider what's in the best interest of Xander."
Holding on to the Slayer for balance, Xander pulled himself to his newly clawed feet. Everyone stared at the transformed young man, complete with the fur, buck teeth, tail and black eyes of a squirrel.
Staring into those merciless orbs, Giles felt a shiver go down his spine. Somehow, despite the small stature of real squirrels, Xander had actually grown two inches and they were now at eye level.
Shakily at first, then with surety, Xander walked over and drew a mirror out from behind a cabinet.
Gazing into it, he jumped slightly then rolled his eyes when he realized it was the enchanted mirror that revealed people's true nature. Grumbling, he fumbled behind the cabinet and pulled out a normal full-length mirror.
Buffy decided to defuse the tense atmosphere with humor. "Anya and I have been talking," she said, her arm about the waist of the ex-demon. "An' it's settled. You need to move to L.A. and join up with Angel."
"What?" Xander shrieked, the hairs of his tail bristling in all directions. He paused, looked in the mirror and decided he liked the effect.
"Honey," Anya said. "You need to be in a place with skyscrapers. Sunnydale is just too two-dimensional for you." She held up a bandanna-mask with eye-holes cut in it. "Look, I still have the superhero outfit you used on the anniversary of our first movie-date."
Looking at the sparkle in Anya's eyes, Buffy dropped her arm and side-stepped away, muttering about too much information.
Rupert Giles retrieved his glasses from his face and began to give them a good polish. "Does anyone else find it slightly disturbing that some of Anya's sex toys are in my shop?"
"Ewwww!" Dawn said, backing away from the adults, until her foot bumped a certain book on the floor. "Oh, look!" She picked it up and showed the room the open pages. "Jell-O!"
Deep Waters (200 Words)
Xander held his breath and dove into the ocean. His webbed feet propelled him forward, his whiskers sensing the currents of least resistance. He scrounged the rocky bottom for awhile before returning to the surface with his prize. Bobbing to the surface he gasped for air before making his way to the sandy shore. "Here you go, honey," he said, presenting to Anya a sizable pearl complete with the oyster that had grown it. She squealed in delight and hugged him.
Xander's furry face gave a half-smile as he patted her back. "I'm glad my being a were-otter helps make you happy but, if it's not too much to ask, could you please 'find' the keys to the boat now?"