"You're afraid... that I am the new man of tomorrow."
- Magog, to Superman
If David Reid's personality had to summed up in one word, it would be 'intense.' He's internalized his identity as a U.S. Marine to his core, and even after his death and subsequent rebirth, he's never seen himself as anything but a soldier. David's views of good and evil are black-and-white, and he is implacable in his convictions.
Magog is not a very likable person. He focuses on missions with stark single-mindedness and tends to push people away with his abrasive attitude and confrontational candor. Ironically, he is much more of a team player than he lets on, and while he is definitely an alpha male, he is also willing to step back and let someone with more experience than him call the shots. The trick is, Reid has to trust that person first - and earning his trust isn't exactly an easy thing.
As a warrior Magog is brutal and decisive. He does not try to reason with his enemies; he simply breaks them, dispensing 'justice' without hesitation or mercy. This is not to say Reid is a violent psychopath - he has compassion for the innocent and views it as his duty to protect those who cannot protect themselves. But his golden rule is “Treat others as they treat others” – and he practices it religiously.