Annoying dog, similarly to its canon form, is a running gag of Underfell. Papyrus may own it in some versions of Underfell.
The dog is little larger than its form in Undertale. Its appearance is quite similar to its canon counterpart, although it is rarely seen smiling. As in Undertale, it represents canine enemies in a select few of their attacks. Its face is often grim, of a neutral expression or frowning. It is rarely seen around Papyrus.
This dog is more mellow and depressed than his Undertale counterpart. It is still an irritation to most characters, however. It vainly attempts to assist them, getting in the way more than being of use. Like its canon counterpart, it often appears in unexpected places, most of which are meant to be humorous. Similarly to Flowey in Undertale, it follows the Frisk around. The dog, however, does not burrow underground. Unlike Flowey, a brief, obvious cutscene will play, involving the dog exiting the screen in a strange way. This includes flying, no-clipping through floors, and time traveling.
Powers and abilities
He possesses the same abilities as in Undertale (absorbing and masterful dramatic exits).
Unlike his Undertale counterpart, Papyrus will harm the dog rather than scold it. The dog is always trying to help, but it doesn't know that it is a great annoyance to Papyrus.