Complex sentence: Though Billy is more friendly towards him, Mandy treats him like a slave, and this angers and irritates him to the point where he constantly fantasizes about killing both of them; however, there have been instances that show that he does indeed care for them.
Split into simpler sentences: Though Billy is friendly towards him, Mandy treats him dominantly, and this angers and irritates him to the point where he constantly fantasizes about killing both of them. However, there have been instances that show that he does indeed care for them.