Hades

In the Underworld, Hades is aided by his two shapeshifting lackeys, Pain and Panic. The two fear Hades immensely and are used as punching-bags during his outbursts, typically as punishment for their incompetence being a recurring hindrance in Hades' schemes.

Hades is hot-headed, both figuratively and literally. When relaxed or upbeat, his flaming hair and skin retain a calming blue color. When angered, his hair and face become a passionate red/orange.

Hades is generally calm, cool, and collected. Though his machinations are cruel, Hades' informal approach to villainy makes him a widely comedic character with a self-aware and irreverent style of humor (though his jokes are usually played for his own, twisted amusement, and at the expense of others). 

However, this is partly surface-level; Hades is eternally bitter and imperious, with his most famous trait being his uncontrollably fervid temper.

Even so, he's an honest god and keeps his end of the bargain with every deal, no matter what the stakes are.