[He didn't know any of that. There's no reason he should have. Still, he feels guilty for not having to guessed, or suspected. He listens to the end, though at some point he has to look away, focuses on a scuff at the tip of his shoe. But he's still listening.
Demigods are not usually blessed with long, happy lives. So what if he's flippant about his mortality? So he's been reckless. He summoned a bunch of skeletons once and dropped like a stone - he's stronger now. He let Lycaon shred his arms so he could jump through his shadow puddle - it had to be done. And maybe his current quest is a little suicidal. (Okay, Hades was preparing a room in Underworld for him because even he didn't think Nico was going to make it - but he did.)
But it's all excuses in the end. Because yeah. He gets what Phanan is talking about.]
I... I'm sorry... [He doesn't know what else to say, or what he's apologizing for. Maybe everything. He hunches down.] I think I'm getting better sometimes. I have friends here. And Chuck. And ... and you. And nothing's trying to kill me. I don't understand why I still... [He shrugs off the rest of his sentence, the way it wavered at the end and how the last word cracked.]