Treecats and the rest of the Honor-verse were created by and are I believe owned by David Weber.
Buffy the Vampire Slayer and all associated characters were created by Joss Whedon and are owned by Mutant Enemy.
Response to Twisting the Hellmouth challenge "A Special Pet For A Special Girl", although it should be stated that no Treecat would ever consent to being a mere 'pet' for anyone...
Myths & Legends
There is a story told by the Sun Leaf Clan about a brave and experienced hunter and scout named Fire Heart, who ventured far from his home and found a dark cave that The People had long kept away from. He could feel the darkness within, but his sence of adventure overwhelmed his fear and slipped silently inside. There are few things that Fire Heart hadn't faced in his long lifetime; he had battled Death Fang's many times with his kin, but there was something within the darkness that sent a chill down his spine, and he flexed his claws nervously.
Deeper and deeper into the cave he crept, ready to spring into action at a moments notice. Darkness had enveloped him, muffling even the clicking of his claws on the cold stone. Moving deeper, he passed the point where he could still see the sunlight behind him, but another, paler light started to come from ahead, and he headed towards it with renewed determination and sence of purpose. He could sence many strange and inexplicable things ahead, but his sence of adventure and curiosity drove him on. Passing out of the darkness, he found himself exiting another cave in a small valley, with a large, single moon overhead, it's pale light casting long and deep shadows.
Something moved in the darkness, its mind glowing as bright as the big-sun, moving as fast as a charging Death Fang. It collided with a creature of darkens, something that's mind was as black as the first ones was bright. There were strange, having only two arms and two legs, and no tail that Fire Heart could see. Their battle was short and violent, the brighter of the two gaining the advantage and stabbing it opponent in the chest with a sharpened tree-branch. The other creatures mind-glow flared like a freshly struck flame, then it vanished like mist in the dawn sunlight.
A second dark-creature crept through the shadows, attempting to ambush the bright-one, and Fire Heart felt compelled to intercede. Leaping from the cave mouth, he struck the creature with all his might, sending it rolling over backwards. He lashed out with all of his claws, his teeth tearing foul-tasting flesh as he battled for supremacy. The creature was strong, far stronger than it had first appeared, but Fire Heart had the advantage of surprise and a lifetime of battling Death Fang's and other dangers faced by his Clan. The bright-one regained her weapon and turned to face Fire Heart and his opponent, surprised at the newcomers appearance. And although Fire Heart could not sence her mind as well as he could one of The People, he was able to convey to her that he was a friend. Striking as fast as lightning, the bright one plunged the tree-branch into Fire Heart's opponent and it's mind-glow likewise flared before it to vanished.
Fire Heart and the bright-one stood looking at each other, unable to communicate, but joined by a strange sence of oneness and joined purpose. The beat of their mind-glows became as one, a connection that none of The People had ever felt with an outsider. There and then they became on in purpose and spirit.
Only once after that did Fire Heart return to his Clan, to pass on what he had learned with the Memory Singers. He brought his companion with him, introducing The People to the strange bipedal creature. They could feel her mind-glow, so strange and unlike anything they had ever felt before, but strong and filled with purpose. They listened to Fire Heart has he told them of the things he had seen and done in the strange place, and how he had felt a connection to the stranger he had not felt since his mate, Dances In Moonlight, had died. Contemplating all they had been told, the Elders named the stranger 'Stalks The Night', and made her an honorary member of the Sun Leaf Clan. Escorting Fire Heart and Stalks The Night back to the cave, the Clan Elder bid farewell to their brother, and neither oft hem were ever seen again.
Honor sat back in her chair, shocked at what she had just been told. Samantha sat on the couch opposite, Nimitz curled up asleep at her side. The hour was getting late, and a storm was brewing outside of the protective dome that shielded Harrington Steading from Grayson's potentially lethal atmosphere. Real wooden logs crackled on the fire, and the ever present Armsmen stood watch by the door. It had taken a long time to translate the legend into the still rather rudimentary human/treecat sign language, and there were sure to be gaps and mistakes. Still, Samantha seemed convinced that Stalks The Night had been human, from a time long before the first hyperspace-probes had been sent out into the void, let along the colonisation of the Manticore system and Sphinx itself. Collecting her thoughts, she careful signed back.
"Do you know the name Stalks The Night used for herself?"
Samantha looked thoughtful for a second, and then responded with equal care and a hint of reverence.