He just hated the things in his head. The images. The sounds. The smells. (2.10)
This is before Mark has the Flare. Hatred brews in these characters like no other emotion; it's created initially by the sun-flares, but grows larger and larger from the other events that transpire.
He pictured Darnell, that dart sticking straight out of his shoulder. Mark wished he had more than a wrench in his hands. (7.19)
Maybe it's because Mark would probably be able to attack the people on the Berg easier if he had more than a wrench. True. But part of this quote refers to Mark's inner rage. He wants to beat the snot out of those Berg people.
Rage explodes inside of Mark and he fights back at whoever hit him, swinging his arms wildly until he connects twice. (20.37)
Mark's explosive rage often appears when he's fighting. Though the Flare affects his brain, it seems like rage is a natural characteristic of Mark's Mark-yness.
"You need to stop or they're really going to kill you. What good will you be to us if you're dead?" (24.17)
Alec also has lots of hatred and rage pulsing through his old veins, but it often isn't used correctly. Here, Mark is telling him to stop fighting because he'll be killed.
Mark felt rage, too. Like nothing he'd ever felt before. Like a storm erupting within. (41.16)
"Like a storm erupting within" is a good way to describe how the Flare fuels Mark's rage. The storm is inside his head, his blood, his arms, his legs—everything is ready to blow.
Something had changed for Mark. His thoughts were purely focused on the man in his grip and on making him pay for everything. The anger was like a fog that had filled his head. And he couldn't stop himself. (42.17)
This is the most hateful, rage-filled moment of the whole book. Mark gets so angry at some guy that he wants to torture him. Think this is because of the Flare? You betcha.
"This was… different. For a second it felt like it was Christmas morning, watching a guy get crushed to death." (45.43)
Hmm, that's… unsettling.
Mark doesn't let himself look at the boy. Instead he stares at the man who killed him, hatred clouding his vision. (47.6)
Here, Mark is staring at the man who killed Baxter. Though fear is probably the first thing most people would feel, Mark feels hatred, which points at how he's naturally filled with immense anger and frustration.
Mark started dragging him down the hallway, aware on some level that he himself had crossed into territory from which he wasn't sure he'd come back. (65.31)
Despite being aware that what he is doing is completely wrong, Mark can't push down the rage that erupts within him. Hmm, that ain't good.
Mark had never known such hatred for anyone, and in some faint part of his psyche he knew it wasn't quite rational. But he loathed the man, and wanted him dead. It was the only goal in his mind. (66.16)
Convinced Mark has anger issues yet? Well, we hope you are now.