Who is Dogbert?
Genetically
he may be a dog, but Dogbert is no man's best friend. He treats
people with disdain, reserving special contempt for Dilbert, who's
no master--or match--for Dogbert. (Although he wouldn't admit it, if
push came to shove, he'd protect the bumbler. And never let him
forget it).
His not-so-secret ambition is to conquer the world and enslave all
humans. He anointed himself St. Dogbert, and as such takes special
delight in exorcising the demons of stupidity.
Why is Dogbert important to Tom?
Well, basically, Tom is genetically a human being, but in his mind he too wants to conquer the world and enslave all humans. At night, when the humans are asleep, he can often be found tormenting the cat, chasing it up trees and the like, or eating Chappie directly from the tin. Also, if you observe Tom closely, he turns round and round in circles when he goes to bed - a vestigial canine response to flatten down the grass before going to sleep for the night.
Really, Tom should be in a kennel, but his
repeated good marks at school seem to have tricked the foolish
humans who masquerade as his teachers into persuading even his own
parents that he is truly a real human being.