Jason Grace and Tyler Jones are more or less the same character, and reading them in comparison is heartbreaking.
Not only their appearance is nearly identical (just one has the scar on the mouth and the other one on the eyebrow) and the fact that they have an older, rebellious sister, but their characters are identical.
Both are the sons of respected leaders, Jupiter and Jericho Jones, and both have to live up to their names. This brings them both in leading positions at an extremely young age. Both train themselves merciless and are, in the beginning of the story, already the perfect hero. Selfless, caring, smart, strong, you name it.
Their journey isn't about training, loving themselves or learn to trust in others, like for many other characters, but to let go a bit of the picture they build around themselves, because they felt like that's what the universe wants. They learned that it's sometimes okay to break the rules and get a bit of the trail. And they both learn it and start to love it.
But then the turning point. Both are ready to sacrifice their lives because that's what heros do. But Tyler survives and gets a chance to live his life. To learn how it is to not only be perfect, he even gets into a relationship that is far from what people would like/expect. Meanwhile, Jason dies. He NEVER gets the chance to learn how to live with this newfound freedom. He never really had a chance to discover it. Jason died for the forced expectations pushed on him while Tyler could break free, at least a bit.