Vulkin
Vulkin is a minor returning character who appears in Chapter 5 of Deltarune.
Vulkin resembles a volcano. Lava can be seen spewing out of the top, and the Vulkin is constantly smiling and blushing.
Vulkin's sprite is unchanged from Undertale.
Vulkin seems to be cheerful, but dialogue reveals that this may be because the character is full of chili.
During the Festival in the cafe, Vulkin expresses enthusiasm, but is actually full of chili. Susie notes that their job seems "cool".