Physical Appearance
This varies greatly depending what Sine is copying at the moment. Sine's true form must resemble something akin to a human from Earth, as indicated by its mimicry of its late parents. Sine's mother and father are by and large its most preferred forms, and it feels comforted to take these forms and look into a reflective surface. Over time the voices have distorted and withered, his mother's high laugh turning shrill, his father's smooth hum growing lower like gravel. Such is what happens when a memory is replayed over and over without any refreshes.
Sine's Mother
Sine's mother had a lanky frame, and was thin. Their cheekbones were very pronounced, and they wore their hair short and wavy. Despite their old age when birthing Sine, they preferred a youthful appearance, keeping their skin youthful and clear of wrinkles, never one to belie their true nature. Their hair would be a deep emerald one day and a fiery orange the next- sometimes oscillating in the middle of a conversation to suit their mood, much like their eyes- going from a hue of the ocean to the deep indigo of a fading sky. Sine's mother bore gills discreet upon their neck and chest, and only the lightest of reflective rainbow scales across their form.
Sine's Father
Whether it was true that they were impossibly tall, or if it was the misconceptions of a small child's view, one cannot say, but the form of Sine's Father towers above many humans, and even some beasts of the wilderness. The father bore four arms and a set of large plumed wings on its back- they belonged not to its natural form, but it adapted them for convenience in protecting his family. His hair was impossibly long, fringed bangs covering his lime green eyes and the rest towering down the length of its body in a silver stream.
Clothing
Sine is critical of their appearance, and often preens and tends to their form, making changes here and there. As such, their clothing could be anything from only the basest of cloths to the most extravagant of ball gowns- but it would always match their appearance and those surrounding them.
Personality
Sine is gentle and soft-spoken, and generally quite curious. Sine has a bit of a mean streak to them, though, enjoying the reactions of those pranked. Sine is competent, if not outright skilled, in battle, enjoying the raw meat of the beasts of the wild as a delicacy, and will not back down from any challenge to their mental, physical, or emotional standing- be the challenge real or perceived. Sine functions well when given repetitive tasks or given something to do on their own, but falls flat in assignments with large groups, as they are unused to the crowd.
History
Sine is the final known remnant of the organic life of Kabott that ruled it before the planet itself failed to heave another breath and fell into decay. Sine's parents both died soon after its birth- an unfortunate guarantee of their species. Often, a clutch is born to offset this, but due to the extreme toxicity in the atmosphere at the time, only Sine managed to survive to birth. Sine was raised primarily by the other remaining lifeforms, knowing only what they were taught by theml survivors, and have only the fuzziest memories of their biological family. Now only a lone mimic remains to wander far from its carcass of a planet.
Abilities
Sine is able to change their form to accommodate any mix of biological characteristics they can see on a live specimen. [Doing so to another muse in the rp does require OOC consent, for mimicry in whole or in part.] They are also able to blend into their surroundings as a chameleon would, and can even learn to develop resistances to toxins they are exposed to within a controlled environment.
Weaknesses
Sine is extremely gullible, and knows only the most instinctual use of their abilities, meaning that they often can literally destroy entire organ systems accidentally when mimicking something for the first time. [I roll a d4 to determine if it would be from respiratory, gastrointestinal, cardiac, or filtration. This does not go into effect for purely cosmetic changes, such as a slight change in coloration or external features/appearance.] The process of mimicry is also painful for Sine, as the entirety of their insides and outsides must change. Sine also has no natural defense mechanism to stop injuries- if they are stabbed, shot, or burnt, it will heal like any other injury would, and will die of severe attacks. Sine would also be fairly incompetent socially, unable to function well in any capacity of society, or properly communicate with others without being taught how. However, from observation or teaching, this weakness will be completely eradicated due to their adaptive nature.