When Yao commented Ryland Grace speaks like a child, there’s a reason why he’s a good teacher. He’s an adult with childlike wonder who knows how to make everything fun that makes them worth doing.
He tosses a little earth ball and calls it lava, refers to astrophage breeding as whoomp, there it is, plays around in the hardware store and buys a ton of skittles, You’re not gonna believe this… Nothing happened! He’s not hung up on being serious at all. Shit, he’s not even doing the scientific method systematically and skips ahead. He operates on vibes. His maturity is shown through his work and results, not his methods.
That’s why when reality hits he acts very hesitant. Suddenly the situation escalates and his reaction is I’m not doing that. In fact, Ryland Grace was already dodging the important shit in the first few scenes. The students were asking if the sun’s gonna die and it took a lot of reroutes before he finally caved in.
The rest of the Project Hail Mary felt like grownups. He thinks they’re putting themselves out there more than him, making big choices. He might’ve felt like he’s being treated as a resource, a coworker, not a friend. Like he doesn’t belong in the project, that it’s too serious. So he’s fine being in the sidelines. In his comfort zone. Now remove him from the comfort zone.
The reality is not enjoyable so he has to cope with that. He hates moments of dread. He hates darkness. So he acts like sunshine and rainbows as much as he can. Like a child.
I’m not saying Ryland Grace doesn’t know the gravity of the situation he’s in, he just doesn’t want to feel it.
Arguably, his biggest reasons for doing things are curiosity and care. Curiosity is easy. Caring is harder especially when most people you’re with mostly care about what you can do and not who you are. Rocky cares, he cares about Rocky. That’s enough for him to be fine with the dread, do something about the darkness, all while acting like sunshine and rainbows.