In Dark Sun half-elf gain the ability to get a companion when reach the third level. Usually, the companion can't be a strong creature 2 or 3 HD, with some special abilities. However, in my oppinion there is few creatures that match for a good companion, so i created a new one. I hope, that you like this creature. 
Meriath
Small-Size Magical Beast
Hit Dice: 2d10 (11 hp)
Initiative: +9 (+5 Dex., Improved Initiative)
Speed: 40 ft.
AC: 16 (+5 Dex +1 size)
Attacks: 2 claw +3 melee or 1 bite +3 melee
Damage: claw 1d3, bite 1d4
Face/Reach: 5 ft. by 5 ft./5 ft.
Special Qualities: Chameleon, Traceless
Saves: Fort +3, Ref +7, Will +1
Abilities: Str 10, Dex 20, Con 10, Int 10, Wis 13, Cha 17
Skills: Hide +10, Spot +9, Move Silently +13, Search* +9, Sense Motive* +8
Feats: Improved Initiative, Run
Climate/Terrain: Rocky Badlands
Organization: Solitary, or Gang (1d6)
Challenge Rating: 2
Treasure: Standard
Alignment: Chaotic Good or Chaotic Neutral
Advancement: 3-5 HD (Small-size)
Meriath is an intelligent creature and looks like a weasel, with a small browning skin, with dark yellow "hands" and brown tail. When someone see Meriath in the first time, thing that is sweet, inoffensive and innocent creature. Well almost, Meriath is a thief, he stolen food but sometimes he catch small bright things only for fun. Athas is a hard word and this creature survive only due to your ability to run and hide. Finally, Meriath avoid the combat at all cost, because it things that usually don't have any chance to survive in combat against another creature.
Combat: Meriath is a small, weak but fast creature. However, Meriath is an intelligent creature that known exactly her abilities, what means that Meriath avoid combat at all cost. If other creature hunt Meriath it use chameleon power to run away of your enemies and stay immobile until the predators go away. However, if Mariath is discovered or forced into combat use it claws, but soon is possible will running to escape.
Chameleon(Su): Chameleon works like chameleon psionic power. In other words, the meriath receive +10 enhancement bonus on hide check. However, in addiction if meriath remain immobile receive +20 enhancement bonus (this bonus don't stack with earlier bonus). Also when meriath active this power, can't be track be scent. The Meriath can activated this power 3/day.
Traceless(Su): This power allow Meriath to pass in any kind of terrain and don't let any trace. Meriath can activated this power 3/day.
Meriath
Small-Size Magical Beast
Hit Dice: 2d10 (11 hp)
Initiative: +9 (+5 Dex., Improved Initiative)
Speed: 40 ft.
AC: 16 (+5 Dex +1 size)
Attacks: 2 claw +3 melee or 1 bite +3 melee
Damage: claw 1d3, bite 1d4
Face/Reach: 5 ft. by 5 ft./5 ft.
Special Qualities: Chameleon, Traceless
Saves: Fort +3, Ref +7, Will +1
Abilities: Str 10, Dex 20, Con 10, Int 10, Wis 13, Cha 17
Skills: Hide +10, Spot +9, Move Silently +13, Search* +9, Sense Motive* +8
Feats: Improved Initiative, Run
Climate/Terrain: Rocky Badlands
Organization: Solitary, or Gang (1d6)
Challenge Rating: 2
Treasure: Standard
Alignment: Chaotic Good or Chaotic Neutral
Advancement: 3-5 HD (Small-size)
Meriath is an intelligent creature and looks like a weasel, with a small browning skin, with dark yellow "hands" and brown tail. When someone see Meriath in the first time, thing that is sweet, inoffensive and innocent creature. Well almost, Meriath is a thief, he stolen food but sometimes he catch small bright things only for fun. Athas is a hard word and this creature survive only due to your ability to run and hide. Finally, Meriath avoid the combat at all cost, because it things that usually don't have any chance to survive in combat against another creature.
Combat: Meriath is a small, weak but fast creature. However, Meriath is an intelligent creature that known exactly her abilities, what means that Meriath avoid combat at all cost. If other creature hunt Meriath it use chameleon power to run away of your enemies and stay immobile until the predators go away. However, if Mariath is discovered or forced into combat use it claws, but soon is possible will running to escape.
Chameleon(Su): Chameleon works like chameleon psionic power. In other words, the meriath receive +10 enhancement bonus on hide check. However, in addiction if meriath remain immobile receive +20 enhancement bonus (this bonus don't stack with earlier bonus). Also when meriath active this power, can't be track be scent. The Meriath can activated this power 3/day.
Traceless(Su): This power allow Meriath to pass in any kind of terrain and don't let any trace. Meriath can activated this power 3/day.
