Slate

-He collects figurines like a middle schooler. Don't touch his shelf.
-He's always had a habit of getting obsessed with random things. Mortus likes to keep track of all of his phases on a designated notepad.
_{(Let's see... The Nintendo-bro phase, the "I'm too cool to listen to my dad" phase, the "fuck ducks I fucking hate ducks I'm going to eliminate all the ducks, its for the good of mankind" phase, the Terminator phase... Wait hold up that one is a little concerning, like, should we be worried about that-)}
-He almost always helps his creator with his experiments. He's quite helpful, as Mortus himself is remarkably short.
-You can remove his helmet. It's not permanently connected to his head, although it does snap in place like a puzzle. It serves as his main power source. Without it, he can survive, but he will be a bit slower and stupider. Oh well, at least he can canonically get a haircut. Yay!
-His right hand can be used for a variety of things. These can range from it withdrawing objects like swords and other weaponry, to literal whisks (He's got cookin' to do).
-Slate can be quite oblivious to a lot of things. He's trying, bear with him.
-He has a bad habit of speaking to any "robots" in the area, regardless of their function. He loves speaking with the toaster in the laboratory kitchen (...He feels sorry for the thing and swears on his life that he will "save" it one day).