Glass

The symbol on his forehead changes depending on something. He doesnt actually know why it does, and how it does or what it looks like when it's happening.

Similarly, he cannot look in mirrors. It's not that they don't work, but he gets seizures when he does.

The black parts will leak when Falling or Lesser Kind is nearby. he also doesn't know why.

A lot of things about him, he doesn't know the reason for.