You must learn a special skill to tame Lesser Dragonkin. For pets of this family other than cloud serpents, the skill is taught by the tome, How to Train a Dragonkin. This is awarded by Kaestrasz in Valdrakken at renown level 23 with the Valdrakken Accord. It is only awarded to hunter characters with the appropriate renown, you cannot achieve the renown on a non-hunter alt.
This rarely-occurring fey darter spawns in the upper caverns in the far south-east of the instance. If it's present, head south-east, go past Skum, and follow the ramp up and around until you find it. The orange variant of this creature occurs roughly 1 in 5 of the times it spawns. You can '/tar Deviate Faerie Dragon' from just inside the dungeon entrance to check if it has spawned and if it's in the colour you're after. If not, you can leave, select "Reset All Instances" from your character portrait, and keep trying. Note: you can only target it from just inside the entrance, and in the south-eastern third of the dungeon; once you proceed past the NPCs at the dungeon entrance you won't be able to detect it again until you head further south-east again.
Hostile to both factions. This fey darter appears only sporadically in the area, and is often killed by hostile NPCs. It may take you a while to find one.
Found in caverns just south-west of the Gardens of Unity.
Level scaling: Most NPCs will scale with the Hunter's level, within the constraints of their level range. Hunters can tame regular NPCs up to 2 levels higher than them, but can only tame elite NPCs of the hunter's level or below.