Biology, culture, and natural history
The hrihriwa are a race of human/horse shapeshifters. They live in clans of a few dozen to several hundred individuals and often incorporate humans and horses into their clans. They are found all throughout the Rootspan, but tend to cluster in remote and inhospitable areas, particularly in the central root mountains and on the steppes of the outer ring.
Anatomy
At a quick glance, a hrihriwa may seem like a regular human or horse (depending on their chosen form), but both of these forms have distinct traits that set them apart from your run of the mill human/horse.
As humans, hrihriwa have large, pointed ears, which move in response to their emotions. They may pin their ears against the skull in fear or fury, flare their ears in excitement, or flick them in annoyance. This is a semi-conscious movement, like facial expression, and may be controlled with great willpower.
In their human form, hrihriwa also sport rather large eyes, always in seemingly-impossible colors. They span the entire chromatic spectrum, from red to yellow to blue to magenta, and always highly saturated. Their hair spans the entire equine color spectrum (and is of a similar wiry texture as horsehair), while their skin spans the entire human spectrum.
There is very little sexual dimorphism between their males and females (or 'stallions' and 'mares,' as they call themselves). Mares have very small chests, somewhat boyish hips, and a tendency to grow sideburns. Stallions have narrower shoulders and wider hips than most human men (though this point of difference is not very pronounced), and are unable to grow full beards. They're of average height, compared to humans, though of a slightly more wiry build. Both sexes have the same height and same muscular stature.
As horses, they retain their brilliant eyes, including the white scleras and round pupils, which may be a disconcerting sight on a horse to the unitiated. They're of a rideable size (the only rideable equines in the Rootspan), tough they loathe to let anyone ride them. A hrihriwa's horse form is typically as tall as their human form, measuring by the poll. Their coat, of seemingly any color found in regular horses, short and without any feathering.
They have a rather light build, akin to a light carriage horse or a lady's pleasure horse, with a high-set neck and a high-stepping bouncy gait. They are gaited, though the full range of their gaits is unknown. When asked, they will simply say that they can walk, trot, and 'run.' Walk, trot, extended trot, canter, gallop, pace, and something akin to a saddle rack or running walk has been observed.
The most distinctive feature of the hrihriwa is their ability to change between these two forms. Their transformation is not instantaneous or logical. Every individual has a distinct transformation process, and they can learn to control the process and degree of transformation. The average transformation lasts 5-10 seconds. It's most common for the transformation to start at the extremeties, though some start at the body core or head. A few apparently start from right to left, or vice versa, beginning with the extremities on one side and ending with the extremities on the other side. However, even with a 'starting point,' body parts may change out of order or seemingly at random, making for a very disconcerting viewing experience.
Biological functions
Eating, breathing, speaking, aging, reproduction
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Natural history
Ecology
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Religion
Religion
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Cultural practices
Clans, gender, diet, clothing
With very few exceptions, all hrihriwa have a two-syllable humantongue name and a horsetongue name that is unpronounceable for humans.