Kid Sid Vicious is a really good description. Though I can't see Dennis stabbing Gnasher to death, then OD-ing in The Chelsea Hotel happening in the strips anytime soon...
It's funny though, both US and UK Dennis' have the same name and same basic premise but were thought up completely separately by their creators and -get this!- were both first published on either side of the Atlantic on the exact. Same. Day.
It made #3 on Cracked.Com's "The 5 Most Mind-Blowing Coincidences of All Time" article a few years back.