Sylven
Details
Sylven is, in the simplest of terms, weird. Born and raised in the wastelands of modern time, the homunculus is the youngest of 29, and the only one born with a strange birth defect-- upon hatching, they never grew the carapace typical of dolls that give them their porcelain appearance. Instead, the nanites comprising them "panicked" and cobbled a solution to keep attracting mates: look the most like whatever that person thinks they should look like! This did not help, as Sylven ended up infertile due to their abnormal physiology.
The creature now obsesses over the concept of Pre-P-Day and all the information relating to it. Reproduction, physiology, society, even naming conventions. They want to know it all. This has resulted in them being unable to tell the difference between scholarly and fictitious media, causing their speech to be very reminiscent of a poorly written anime character.
Appearance
Sylven has an extremely inconsistent appearance. While their overall size and mass is mostly kept stable, no two people are able to see them the same. In fact, this isn't even possible to prove-- strangely, anyone who looks at them is fully able to understand and comprehend them but unable to put that appearance into words. When looking away, the mental image of what they look like disappears. Any attempts to draw them fail, alongside methods such as photography or video. The only exception are very vague concepts-- the fact that they're made of clay, if they're shorter or taller than another person, and their overall human shape.
When looking at them, Sylven's body literally begins to shift to match the perception of the person looking at them. Due to some weird quirks of their nanites, this can be multiple forms at once. They can be clothed and naked, bald and have luscious locks, many-eyed or completely featureless, all for different people. The only limit is the imagination and desires of whoever looks at them. And also mass. The laws of physics still apply to weird clay things.