Hades is the God and King of the Underworld, the head of the Underworld CORP and a member of the 6 Traitors Dynasty. 

Even ignoring the kidnapping of Persephone, Hades in classic mythology was known as a dark, cold, unyielding figure with a wrathful temper towards anyone who crossed him and little interest in anything happening outside of his realm. He wasn't an evil god but he wasn't the affable figure shown in the comic either.  He likes puns, sings to his dog on the way into work, and although Olympus is fully modern he still keeps a checkbook because he enjoys balancing it. Whilst he is generally a nice person (despite most of Olympus being wary of him) he does have a scary side to him. He shows it in episode 49 when he confronts the reporter who took a picture of both Persephone and Hades walking at his house for a tabloid and his form changes from his usual suit clad self to a huge terrifying being. Regularly micromanages his employees, keeping track of their internet usage to make sure they're no slacking off during work and harshly chastises Thanatos for coming in under his soul quota. To be fair on that last one, the pie chart Hades had prepared was showing that Hermes was doing three times the work of Thanatos in collecting souls, despite having other duties.  is usually melancholic. 

Episode: https://www.webtoons.com/en/romance/lore-olympus/episode-1/viewer?title_no=1320&episode_no=1