I absolutely adore and am amused by Malthael. Let me explain why:
After finding the human souls in the Pandemonium Fortress, Malthael goes full on emo, embracing death as his new obsession, even taking on a moniker of "Angel of Death"—! If you've read his diaries in Act V of D3, you know he is yapping nonstop about "ugghhh death is pure and death is true wisdom, death consumes us all blah blah"—
So, Malthael is very into death, then, hmm?
Alongside his new fixation, Malthael is also adamant that he is doing the right thing killing off humanity. They have demonic essence in them and are a threat to the Heavens, so they need to die, he says. Before the events of RoS, Malthael had been planning his genocide for literally DECADES, pouring an immense amount of scheming, resources and manpower to achieve his "noble goal" of ending the Eternal Conflict.
Okay, so Malthael is fixated with murder AND he genuinely believes that he is righteously saving the Heavens with his deeds with the black soulstone.
Still with me? Good. Here's the FUN PART:
Despite all of the "noble, wise Angel of Death" -facade that Malthael has put on... HE IS A DAMN COWARD.
The Nephalem clashes with him in battle, and Malthael notices that "oh shit this mortal is pretty beefy, I might die in this fight". You'd assume that as someone who is very intimate with death and extremely determined to slaughter humanity for the greater good, Malthael would simply… choose to stall the Nephalem as long as he can, even if it might kill him. It would NOT be an issue. Malthael knows that his soulstone is active, and it is eradicating humanity as they speak. The majority is already dead. Even if the Nephalem were to kill Malthael, they would be TOO LATE. The soulstone would have finished its job already. Malthael would have WON, even in death. His own life is a minor sacrifice to achieve his grand goal.
But NO. No, no, no, nonono…. Hahahahaha—
Instead, INSTEAD, like the itsy bitsy little coward he is, Malthael just... ABANDONS his WHOLE ASS PLAN, retrieving the black soulstone and using it in a desperate attempt to save his own skin. Decades of planning, countless dead followers, becoming an enemy to the High Heavens themselves... Each and every sacrifice just… down the drain, simply because Malthael was not ready to die himself.
The Angel of Death, afraid of said death— Malthael had the keys in his claws to end the Eternal Conflict and wipe out the abominations born of demon and angel that threaten the Heavens with their existence…
…but when push came to shove, Malthael weighed his OWN LIFE more precious than all else. Such hubris!
What a fraud, huh? Well, I actually love Malthael for it. It is hilarious yet also riveting that there is something underneath that emotionless act that he puts on.
I wonder just how self-absorbed and prideful he truthfully is. Unlike some certain other angels, Malthael does not really brag about of his own importance. Yet his actions speak louder of it than words ever could.