So, I was thinking about what Will would look like if he was outside of his suit in his ghost form, and this was the result.

...I don't know whether to be scared or embarrassed...

So, the reason for parts of his design is because of his state-of-being.

The bandages represent how his body broke when he got stuffed into the suit. The little ghost-things around him are his hateful thoughts given visual form, and the red crack behind him represents his unending rage towards William Afton. He's covered in blood, and holds a ghostly version of the security tablet he used to use as a Nightguard.

So, yeah, this is Will in his ghost form...I need a life.