Finn's eyes wouldn't be so large unless he was certain. (1.23)
Thisby might seem like a nice unassuming island community, but everyone lives in fear and awe of the vicious water horses that emerge hungry from the sea. We can't imagine a tourist brochure ever making us think this is a hot vacation spot.
The horses drag them around like they have no weight whatsoever. What would they do to me? (7.47)
Puck has a little more fear of the capaill than Sean does because she's never known them not to want to tear people apart, whereas Sean and Corr have a relationship that's downright brotherly.
There she is, trotting up to the knee in the water. Fearless. (15.4)
Despite being scared out of her wits, Puck projects a calm, stoic manner. This is Sean talking, thinking she's fearless, when that couldn't be farther from the truth.
[Dove] could've died. (16.5)
It isn't her own life being in danger that instills fear of the races in Puck, it's the fear that she'll lose her pony and best friend, Dove.
I remember the story we're told as soon as we become teens, of the two teen lovers who met illicitly on the beach, only to be dragged into the waves by a waiting water horse. (21.9)
This story was drawn up by the adults to strike fear into the hearts of the hormone-addled children… as if simply growing up on an island where it seems every child's parents have been devoured by horses isn't enough.
I would like to be terrifying. I glower at [Sean]. (23.39)
Puck tries to scare Sean a bit, but someone who has seen men get eaten alive in the ocean probably won't be scared by a mere hard stare.
"Look! Look there! A head!" And despite ourselves, we all look. The water shifts.
I know I should be terrified of tonight and of tomorrow and of the next day, and I am, but I can feel something else, too: excitement. (28.43, 28.60)
Sean has a hard time distinguishing between fear and excitement. The adrenaline rush that comes with certain death motivates him more than it cautions him to stay away.
Sean said, "I want to know who's afraid of the water. I want to know who can track straight. I want to know who will tear Corr apart as soon as overtake him. I want to know how can't hold their horses." (32.23)
Remember when Sean's dad died and Sean believed it was because of fear? Sean tries to scope out the same fear in other racers, hoping to use it to his advantage and overtake them to win the race.
My body warns me of the danger of this capall uisce beneath me, but at the same time it screams that it's alive, alive, alive. (47.30)
Now Puck is feeling the same adrenaline rush that keeps Sean going. There must be something about being that close to certain death that is exhilarating.
"I can't go into his stall like this or Corr will feel this [fear] on me and I might as well not step onto the beach at all." (58.7)
This is a good bit of misdirection on Maggie Stiefvater's part. We know that Sean's dad died because he couldn't control his fear, and here, she seems to be trying to get us to think the same thing will happen to Sean. Your fear mongering won't work on us, Mags.