Katai is average height for a male (about 5'8") and very muscular. His skin is a very dark brown. His hair is black and layered and feathered in a curious fashion, but the longest parts fall just below his jaw.
He has golden eyes with vertically slitted pupils, due to the demonic nature of his body. He does not bother to wear contact lenses to hide this; most people simply assume that he is wearing them already and that they are costume lenses.
Katai's wings are bright red and not quite as large as his body is. He usually folds them away due to his empathy, which is explained below.
Katai does not have an extensive wardrobe. He is nearly always shirtless and in bare feet. His pants are always very simple and nearly always a bright red similar in colour to his wings (whether or not they are presently visible). Katai does not like to cover his body if he can help it; he loves the feeling of the elements on his skin.
Put simply, Katai is one of the most sweet and kind people in existence.
Katai believes that almost everyone has a certain degree of innate good (at least in the Mortal Coil; his opinions on beings from Heaven and Hell are much less forgiving or gentle). He is kind and generous; this would mean that he gets taken advantage of, however Zade is usually not far away and manages to stop such things happening.
Katai is rarely seen without a gentle smile on his face. He is a very caring person, and would be very much open to hugs from everyone if Zade didn't have rules about who can touch Katai and where and for how long.
If he'd been born in the Mortal Coil as a human, Katai would have grown up to be a filthy hippie.
Katai is a dengel?, and more specifically he is an angel that was born into a demon's body.
He was born in Hell but quickly escaped from there to Heaven, where due to his demon body he was shunned by the angels and God, Goddess and Gods. Having no place to belong, he went mad for a couple of hundred years and killed a lot of angels and demons both. Somehow (and it has never been revealed how) he found his way to the Mortal Coil where his sanity returned.
Most of Katai's history is shrouded in mystery, even to Zade. Katai doesn't like to talk about his origins, insisting that it's a "boring story, and an unpleasant one as well".
Katai understands and somewhat relates to Zade's "condition". The energy of a demon (and a demon's body) is extremely masculine, where angelic energies are feminine. Katai is not mentally female in any capacity; but his core self is very effeminate and loving, something that his demon heritage does not allow. This is one of the reasons he is as shy and socially awkward as he is; his genetics and mind are constantly at war with each other about how he should act.
Katai and Zade have an understanding: Katai is Zade's best friend and the only person who understands him and gets to know his secrets, and in return, Zade is an overprotective bastard who won't let anyone within two feet of Katai without a permission slip.
Katai cares for Zade very much, moreso than most people. They are best friends, in the truest sense of the phrase. Katai was actually the hero in the beginning, helping Zade get accustomed to his new life as a vampire. Katai understands Zade's complexities without ever having had them explained to him, and because he loves Zade without judgement, he is rewarded with the vampire's trust and love in return.
Katai isn't sure how he feels about Lance. He loves him, that is clear, but whether that love is purely platonic or contains slivers of romance is unclear to everyone involved. It's possible that he could have grown to love Lance in a romantic fashion, but Zade would never allow it.
Regardless, Katai and Lance are very close friends, and very touchy-feely ones at that. They often hug and embrace each other for no apparent reason. Katai clings to Lance for comfort when required (Zade is not especially cuddly).
Katai has a very important connection with plants of all kinds. His empathy extends to plants as well as creatures, and he has a particular fondness for plants in particular. According to him, they are completely without judgement (however those who have been attacked by Bessie? may disagree).
Katai runs a business, specifically, a florist shop that's been around for a couple of hundred years. Why no one ever noticed that the owner never aged is a bit of a mystery. It's possible that he changed locations every few years or so to avoid awkward questions.
Katai grows his own flowers and plants in a greenhouse at the back of his floristry, and loves them as friends and pets. They love him too, and are fiercely protective of him.
Katai is an extremely gifted empath, through no choice of his own. He has been that way since birth, and due to the powerful nature of his empathy he can only barely control it. Even when it is under control, if the people around him are being particularly emotional, Katai will get a severe headache, or even a nosebleed if emotions rage too loudly.
Like all angels and demons in Lance's world, Katai's wings have a degree of innate empathic ability themselves. Because this can cause far too much "noise" to Katai, he usually keeps his wings folded away so they do less damage to him. Should his wings 'pop out' at any point, he will often be overwhelmed by the emotions of the people around him, regardless of how mild they might be.