Casper is the Morality Pet of Hairy Scarey.
Ghost headquarters assigned Hairy Scarey the job of teaching Casper how to be a threatening ghost in hope that Hairy would be able to make Casper a non-friendly ghost. Instead, Hairy became attached to Casper and it ended up having the opposite effect of what was intended (the events of Casper's First Christmas being the turning point), making Hairy become a more friendly ghost who still enjoys scaring people For the Lulz. While he still wants Casper to be scarier like most ghosts are (it is his job to toughen him up), and there are times that he shows some disdain for Casper's friendliness, he really does seem to care about him. Hairy is related to Spooky.
They both have noses that are a different from the other ghosts in that they have a color (Hairy's being red and Spooky's being black), wear some kind of clothing (Hairy has a bowtie and Spooky has a hat), both enjoy scaring people and have ties to Casper...