Oh man he really gives really gives off good boy vibes! Honestly, I really like the way you’ve written him. I can tell you’ve taken a lot of care to build up his relationships. The one with his sister makes a lot of sense, and with his father too—he was an adult who betrayed him and his mom and his sister, so of course he’ll get on his nerves. 

I also really like the line “Then again, at the end of the day, he's a teenage boy dealing with the end of his senior year and (much to his dismay) the upcoming end of the world.” Both problems seem like they’re on the same scale, and that’s a) hilarious and b) Man, everything really does seem like the end of the world when you’re a high school student.