His build is svelte, old terrans might refer to it as a 'swimmer's build'. He stands on plantigrade paws and he could even be considered cute, if a bit goofy looking in his deep brown eyes and his large attentive ears. His occupation, which is fairly easy to see, may override any original opinions.
Rheoryn is a shaman. His face painted over with a morbid white skull that sparkles unnaturally. The thing looks vaguely like some sort of strange reptile creature. Large fangs dip down across his muzzle, imitating as if he was actually wearing a skull. He wears several pouches and belts in a throwback to ancient days, well except they didn't come in PVC at the time. He seems to carry numerous herbs and incenses with him, though those twinkle and glitter oddly in the likely. Likely they're nanites more so than any 'real' magic.
He is very nearly nude. His fur keeps him warm enough, especially with the Mess's climate control and a simple loincloth of a material similar to the PVC-like pouches. It is draped down and seems to be all he currently wears. Despite his young seeming age, he walks with a staff, though it seems mostly for style or effect of his order. Everything about him looks to be in ancient in style, until one looks closer to see it is made of Mess-age materials.