The first thing you need to know about Matthieu is that they are incredibly hard to describe. This fiend of nature takes the disturbing appearance of a humanoid and a bee intersected though the abdomen and becoming one cohesive creature. But oh, there is much more to it than that, most of which is I will try to explain below:

The Bipedal Sector
Approximately 4 feet tall. Resembles a Human, but not quite. Starting from the top: Matthieu’s (Or "The Boy's", as explained later) head is youthful and delicate but soured by his constant look of either pure apathy or unnerving glee. There is no hair atop his skull, just yellow face markings against a black widow’s peak and dark eyespots. Solid rose-tinted eyes sit cool and emotionless. This all leads to a thin neck, a slender, dark torso, and an impossibly flexible spine. He is a master of contorting his body into all sorts of strange positions, and can even flop around like a ragdoll if he doesn’t want to put in the effort of standing up.

His arms are long (a bit too long) and slim, the same coal tone as his chest. Each finger is long, double-jointed, and suited perfectly for manipulating objects. The palms are gold. Down by his lower stomach, the skin gradually transitions to yellow just before it intersects with his other body– more on that later. Jumping down to the bottom: his human legs reappear after a bit, with a smooth gradient once more. He has wide, pale-soled feet.

The Insectoid Sector
Approximately 2 feet tall and 5 feet long. Indistinguishable from an Africanized Killer Bee. Once again, let us start at the head. The Bee's head is large and fuzzy, a dull black tinged by gold. She has large copper eyes (plus four proto-eyes atop), two antennae and sharp, sharp mandibles. These jaws are capable of speech, though it’s a much deeper, buzzing, and alien voice compared to their upper head. This connects directly to her dark thorax– unlike a regular insect, she has only four legs, and the wings on her back are too small to carry twice the weight. Her abdomen, or “tail”, has six large stripes that slowly fade into gold.

Right at the end of her body is the crowning feature of any bee: a stinger. Don’t you forget: Matt is a killer bee, and one raised to a very large size, so the venom in there is lethal for anything short of a dragon. But thanks to the internal structure of a honeybee, plus the opal stone ringing it’s tip, a single sting would wrench out both her internal organs and her gem. What a way to go.

Convergence
And right where these two forms intersect is… complicated. Very complicated. Bone turns to carapace, flesh falls away in favor of fur, and the internal anatomy’s a biologist’s worst nightmare. Matt’s human torso sits right between the wings and the feet replace the midlegs. Their skeleton is still there, internally, but tightly squished between organs and connecting weirdly to the exoskeleton. Both sets of stomachs connect eventually, as well as the nervous systems, so at least that’s a relief. In the unlikely scenario a head is chopped off the other might be able to survive without chrysalization or death, albeit heavily disabled and somewhat diminished in brain power.

A young Matthieu appears similar to his full-grown form, albeit smaller and with the upper proportions of a toddler. They do not go through a larval stage.

Additions:
-- two long, rootlike scars running down the length of both forearms from failed host casts.
-- slight burn damage across his palms from touching the Spire.
-- a large, but surface-level scar along the intersection of their backs, scabbed over with skin and carapace.

But the core part of Matt's belief is so-called "Constant Motion": everything should change, even by a little, from sleeping positions to ideas to the basic laws of reality. They welcome in the chaos gleefully. The only evil is Stability, and the only villains are those who bring it. They have little sympathy for lawful types.

Adding to this is the fact that they don't exactly have one mind. But not two or more, either; each of their heads is partially distinct but share the same sensory input and limited stream of thoughts. Think of brain-conjoined siamese twins. The lower head is more brutish and identifies as female, while the upper head is sly and sees himself as male. They may internally go by "Bee" or "Boy", respectively. However, the two of them are so closely linked through the nervous system that they act as one mind more often than not, and are perfectly fine identifying overall as Matt. Gender identity fluctuates wildly between the two.

They have a morbid fascination in death and decay. Oil is just so fun to play in! While it isn't to the extent of some other fairies, they don't turn down the chance for a good dead body.

This strange... everything... makes them seem alien and confusing to most outsiders. They hold the same sentiments back. Matt does not form bonds easily, and views what happens to others with a cold apathy. Maybe giggles, if it's funny (or tragic) enough. They toss around the word "friend" easily, but few actually mean more than a rock to him. They don't even have any qualms against manipulating others and lying about how close they are just to get what they want. That's just how the world rolls, buddy. If they like you, they might rank you at "a sparkly rock that looks cool" instead.

A surprising side to this two-headed horror monster is their spirituality. Matthieu is easily inclined towards arcane beliefs, and while they've yet to develop anything in-character, they do display a reverence for insects already. They simply love the poor bugs, and will act surprisingly hostile if someone actively squishes or eat them.