Ryan used to be an ordinary person. He used to be a happy, upbeat boy who always had a way of cheering people up and bouncing back from hardship. That is Ryan no longer. Thrown into chaos alongside his siblings, he went through several traumatic incidents that completely shattered him, both physically and mentally.
And two people are mostly to blame- himself, and Neowise.
Ever since the later half of book 1, Ryan has possessed a psychotic hatred for Neowise, which has led to him coming in frequent contact with him over and over again, leading to life altering injuries every time. Both his bad eye and arm are the direct cause of encounters with Neowise, and have severely disabled him. He can't properly bend his bad arm. And for his eye, aside from constant irritation, he can no longer see the colour blue, instead seeing an impossibly bright, burning, dangerous white he calls 'perihelic white' in it's place. If he looks at the colour for too long, he could experience seizures or migraines. The brightest, most dangerous perihelic white is, coincidentally (or perhaps not) the exact same blue Neowise is.
This, alongside a persistent belief that he's going to die, has completely uprooted his life and destroyed several of his relationships

He's the first protagonist for Kaivasita, and fun fact, NONE of what I just described was planned in advance. All of it was thought up 100% improv.