Another S to add onto my list of "S" as-first-letter-character! He shares quite a similar tail with Shadow, no? That's because he is his son. Mute since birth, Shriek is unable to say anything. And since only Revamp can manage to read his mind, he chose to become his servant and 'earn' a right to be given the ability to speak. He often times believes Revamp when told he is nearing his chance of getting a voice, and has started catching onto the fact that Revamps purposely delaying him. He doesn't want to admit he'd still love working for him after. On top of being mute, Shriek is unable to shift to any form other than the one show-cased here.

Father: http://cortanaretroidex.deviantart.com/art/Shadow-Reference-448321473

At least I'm getting...a BIT better at humans.