Dennis usually gets away with it for a while and then ends up getting a whacking from his father. This involves striking the buttocks, and for which Dennis' father uses a slipper. Dennis' best defense involves sticking a thick book down his trousers. Despite the fact that a book is a markedly different shape from buttocks, his dad never notices.
Over the years a variety of subsidiary characters have arisen, most notable /Gnasher Dennis' spikey dog. There are several other softies also besides Walter, but they are all too pathetic to be worth mentioning.
Dennis always wears a striped red and black jumper which along with his spikey hair has become his trade mark.