Super (SMZ)

omg thank you shes little meowmeow purpol kitty

In undertale, he’s effectively the monster equivalent of an old man doing a massive yard sale, getting rid of shit he doesn’t need. However, due to his old man status “studying history sure is easy” and so he’s the only guy who tells you about the prophecy of the angel and the delta rune, as well as about Boss Monsters.

He also casually mentions he was a war hero back in the day, the Hammer of Justice. Now, two of the items in his shop are the torn notebook and cloudy glasses. These are both items belonging to the human soul of perseverance. Now, he could’ve just picked them up from trash zone, buuut it seems just as likely that he killed that human himself.

This is possibly why he is not in the least bit scared of you on the genocide route. Like, at all. He spits such raw lines as “I wouldn’t buy your chitzy garbage at knifepoint”. He also seems oddly self aware, like more than sans, saying he knows the player cannot kill him while in his shop when threatened. This absolute mad lad will charge you full price for his wares and there’s absolutely nothing you can do about it, and he fucking knows it.