But as they walked away, he was pretty sure that the girl had been singing. She'd snapped, he thought. She'd definitely snapped. (13.46)
Singing: not the sanest thing to do when you're not feeling well. The Flare has a lot of symptoms; your head hurts, you start acting strange, and you get really angry. But singing might just be one of the most common ways to depict a crazy person.
His first instinct is to panic and scream and wander blindly about. But it's a brief moment of insanity and it passes. (14.13)
You don't need to have the Flare to go crazy—remember, the sun-flares were so devastating that madness was everywhere even before the virus was released.
Her tone seemed way too… calm for the circumstances. (23.29)
Another symptom of the Flare: a lot of the characters seem to lose emotion when they're infected. This might just be one of the worst ways the Flare affects the brain.
Not angry or upset; he just said it matter-of-factly, like he didn't think Mark would even considering disobeying. (24.6)
See, a lack of emotion can mean really bad things for the person on the other end. Things that come with no emotion? No morals, no remorse, no limits. You name it.
This was complete lunacy as far as he was concerned, and there was no way to deal with it rationally. (25.26)
Unfortunately for our main characters, the madness they encounter is so out of control that there's really no way to deal with it besides… killing everyone. You'd hope there'd be some kind of mechanism to control the madness (or at least relieve it a little). But nope; the only way to control someone infected by the Flare is to kill them.
His head ached like a storm had erupted inside his skull. (34.10)
Headaches: your number one Flare indicator. If someone even mentions something like my head hurts, then they have the Flare.
There was a wild energy in the room, like they were a nest of vipers, tensing to strike. (37.15)
Another reason why the madness in The Kill Order is so destructive is that the people infected with the Flare tend to work in groups. There seems to be some odd sense of togetherness that comes along with Crank-dom.
There was a moment when everything seemed absolutely ridiculous, like Mark had fallen into a clown act in a circus, and he almost laughed. (39.4)
Ever felt like something going on is so ridiculous that it's laughable? Mark feels this way about pretty much everything that's happening. It's so maddening, he just wants to laugh (pssst, maybe it's because his brain is starting to get eaten by the virus).
He'd been consumed and out of control, every part of him wanting to destroy that pilot. He'd almost been happy when the man was wedged in the closing door… he had the Flare. (43.3)
Here's a great example of how the Flare affects our buddy Mark; he gets so preoccupied with killing the pilot of the Berg that he goes absolutely bananas trying to torture the guy. When he snaps back into it, this is the moment Mark realizes he's crossed the threshold from sane to insane. He knows he has the Flare; he just needs to fight it.
Boredom has settled in like a cancer in the building, ready to eat away at their sanity. (46.2)
Just another example of how the theme of madness follows our main characters everywhere they go. It might be the Flare, it might be boredom, or it might be nerves. It could be anything that generates a feeling of craziness.