While Deathwing was once a benevolent entity, he is now completely evil. He hates all mortal races, and wishes to kill them all. He's also utterly insane, most notably shown when he had the Demon Soul. Deathwing was attached to it, such that even when warned by the goblin alchemists who made his armor that the Demon Soul's energies would kill him if he kept it with him too long, it wasn't enough for him to let go of it, and was only willing to part with, temporarily, when reminded that it would likely be stolen from him if he was dead.

In spite of his insanity, Deathwing does display a degree of cunning. Although he hates mortals, he is apparently willing to tolerate them if it can prove of any help in his plans, though inevitably he will do away with them when they have outlived their usefulness.

Despite Deathwing's overall loathing of mortals, he has respect for, and perhaps even a fear of, Medivh, stating in Day of the Dragon, that he would never willingly face Medivh in combat, though this might technically be fear of the portion of Sargeras locked inside Medivh.

Deathwing is a terrifying opponent who is as cruel as he is vicious. He cares nothing for honor or nobility, striking with whatever weapons and cunning he has at his disposal, reveling in causing earthquakes and ripping open volcanic fissures. He often sends his minions into combat while he surveys the battlefield, striking at whatever weaknesses he discovers.[2]

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