"Sorry kid, nothing personal, just my job."
Lore: he is in the royal guard, and society known for bossing lower ranked people around and slaughtering humans (or even lower ranked monsters), as out the bunch, he is the calmest, but he is the most powerful when enraged, and depending on the route you take, you could make him betray the royal guards (which you make him find out how corrupted they are) But on most runs he blocks his the exit to waterfall and told to kill any lower ranked monster trying to exit snowdin, and when he sees you, he is forced to kill you (or try too)
