Complex sentence: Dogbert was originally just created so Dilbert would have someone to talk to, but as the strip progressed, Adams developed the character to be an anti-hero, metophorically personifying the dark, cynical side of Adams own personality.
Split into simpler sentences: Dogbert was originally just created so Dilbert would have someone to talk to. As the strip progressed, Adams developed the character to be anti-hero, as well as the dark, cynical side of Adams own personality.