Bully

Casey is a bully.  Period.  If Poly is sitting somewhere and Casey wants to be there, he will go and plop himself down, often sitting on her head.  He weighs about twice as much as her and knows it.  She gets her own "bully-ish" time in.  I often catch her biting at his legs.  They play rough and she regularly instigates.  He returns the favor by biting at her legs, too.  When she is feeling playful and he is not, he will go and seek refuge in his crate.  However, more often than not, he is the bully.