I wonder if they'll ever find out what really happened. I've been so busy staying alive I never thought of what this must be like for my parents. (2.63)
The worst part about this ordeal is that no one even realizes that Mark is alive. If they did, he might be a bit more optimistic about his chances. Instead, he sees no way out and loses hope immediately. Fortunately, this fear-induced funk doesn't last long.
I'm going to be setting a fire. In the Hab. On purpose. If you asked every engineer at NASA what the worst scenario for the Hab was, they'd answer "fire." (4.14-15)
Desperate times call for desperate measures. This passage shows how well Mark is able to handle his fear: instead of allowing it to drive his actions, he acknowledges it and moves forward. He could've easily just curled up in a ball and binge-ate his ration packs, but Mark Watney isn't going down without a fight.
There's probably symbolism there. Phobos is the god of fear and I'm letting it be my guide. Not a good sign. (9.26)
Well, Mark summed it up better than we ever could. Frankly, he usually screws thing up when he lets his fear take control and prevent him from making wise decisions. At least the guy's aware of it now.
NASA, however, is absolutely s***ting itself [...] To them, equipment failure is terrifying. To me, it's "Tuesday." (13.57)
What a difference a few months make. Do you remember how frightened Mark was on Day 1 of this ordeal? Look at him now! This passage shows us that courage isn't about not feeling fear—it's about learning to manage it.
"Iris 2 only risks one life. Rich Purnell risks all six of them. I know Rich Purnell is more likely to work, but I don't think it's six times more likely." (16.193)
When we first read this, we took Mitch's side: Teddy is way too afraid of taking risks. The more we thought about it, however, the more we warmed to Teddy's perspective. We still think that the Rich Purnell Maneuver was a good idea, but we understand why Teddy is so timid. If anything goes wrong—either way—Teddy will be the one held responsible.
The worst moments in life are heralded by small observations. The tiny lump on your side that wasn't there before. Coming home [...] and seeing two wineglasses in the sink. (17.97)
Although Mark has gotten used to living in fear, he hasn't exactly transformed into Braveheart. The fact of the matter is that something could go disastrously wrong in an instant, and Mark needs to be vigilant to prevent that from happening. While good, that sort of attention is going to drive you crazy at some point.
I've been in mortal danger for months; I'm kind of used to it now. But I'm nervous again. Dying would suck, but my crewmates dying would be way worse. (18.125)
It's one thing to die, but it's whole different thing to lead five of your closest friends to their death. Mark has long-since made peace with his own possible death: in fact, he never really expected to make it this far. Bringing in other people only raises the stakes higher.
I'm totally exhausted but I can't sleep. Every sound scares the s*** out of me. Is that the Hab popping? No. Okay...What was that!? (20.90)
At this point, fear is pretty much a Pavlovian Response for Mark. The guy has experienced so much crazy stuff since getting stuck on Mars that even the smallest thing gets transformed into a crazy disaster in his mind. He can't let his fear trip him up, however—he needs to keep his eyes on the prize.
I never realized how utterly silent Mars is. It's a desert world with practically no atmosphere to convey sound. I could hear my own heartbeat. (21.167)
Mark's fears are amplified by the fact that he's completely and utterly alone. As every horror movie ever has shown us, isolation has a way of stoking the fires of fear. Of course, Mark has a pretty low chance of running into a deranged serial killer on Mars, so maybe it's a net positive.
In four hours, I'm going to ride a giant explosion into orbit. This is something I've done a few times before, but never with a jury-rigged mess like this. (25.187)
Given that Mark is about to be launched into space with only a strip of Hab canvas separating him from the lifeless void, we'd say he has good reason to be afraid. The bright side is that this will be the last time he has to do something like this—hopefully.