This is not a complete write-up.
Theragons "bond" to their druid partners with pheromones. Coalitionists learn to shapeshift just enough to emit theragon scents - it smells very strongly (musk, a little sweat, a little soil). Trainers have both psychic and shapeshifty talents; training includes the shifty bits as well as group combat (structured, militaristic) and a crash course of theragon biology and culture. Effects of the pheromones: heightened sensuality, decreased sexual interest in own species, increased aggression, territoriality, possessiveness over one's partner, and emotional bond with + trust in partner.
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theragon(s), 20' at the shoulder, quadrupedal theropsids - mammals, known as 'headless dragons' (you'll see why), standard predator body with powerful limbs, splaying clawed paws, glossy pelt (usually earth colors, most typically browns, sometimes greys, black, greens, rarely blues or whites), absolutely huge draconic wings, have live offspring (one or two at a time), long-lived and quick-healing, slight druidic (air-based) inclinations, internal genitalia between hind legs
theragons have a funky tail: long, muscular, somewhat prehensile, ends in claw-ringed pincer with serrated ridged plates useful for absolutely pulverizing food (which is easily ripped from a body with the claw-lining); two small involuntary-prehensile tentacles coil just inside an opening at the base of the pincer / at the tip of the tail, which scoop and guide foodmush into the tail, which is an esophagus; the mush travels through the tail (which can be angled upwards for quick passage, which cannot kink so hard as to cut the passage off to properly-mashed food-puree) and into the digestive system, which is so efficient that all the waste is distilled to a very small amount of acid - which is stored until the theragon either expels the acid in defense from its tail (which is the equivalent of a turkey vulture's projectile vomit) or its 'bladder' gets so full that the theragon lets it drain out of its tail, rinsing its esophagus out with water immediately afterwards. The opening of the tailtip (a natural sphincter, usually openable only by the tongue-tentacles) is the only entrance to and exit from the digestive system.
theragons have a series of reflexively-closeable nostril slits along their bellies and a few just behind their shoulders, all leading to individual windpipes that eventually combine into one solid pipe into each lung. this is not how they smell things.
theragon ears are located just behind the floating ribs; their wings act as giant ears to funnel sound inwards to a handful of small openings that lead into a central 'inner ear' chamber. much of what theragons hear is vibrations through the body. the ear-slits can all close reflexively, usually to prevent liquid from entering and pooling in the inner chamber.
due to so much functionality being removed from the head, theragons don't really have them. their 'heads' are simply the skull encasing the brain and attaching to the spinal cord, but there is no defined neck; the 'head' is a lump protruding past the chest and shoulders. it is distinguishable by only two features: eyes and stalks. The eyes are set into the flesh, strip-shaped and compound, able to barely perceive what is directly in front of them, but unable to move - and the head does not have a neck that it can move. this apparent bioglitch is resolved by the stalks, which serve two purposes: sight enhancement and olfactory processing. Each theragon has 6-8 stalks protruding from above and below its eyestrips; these stalks are hollow and lead to a common olfactory chamber, which is entirely unconnected to the lungs but contains all the necessary receptors to process and identify scent. since this chamber is not part of the breathing process, it is passive and relies on wind pushing scents into the stalks, which is facilitated by the flared, vaned membrane at the end of each stalk. this membrane is also highly reflective and provides a system of mobile mirrors to display images within range of the stationary eyestrips, thus enabling the theragon to see most things around it. the movement of these stalks is prehensile but mostly involuntary; they run on automatic unless the theragon is concentrating on looking at or smelling something, in which case they move in unison to enable that action.