"Luke?"
"Yes?"
"Whatever happens...will we always be friends?"
"No."
"No…?"
"Family. We'll be family.
"Promise?"
"Promise."
⁂⁂⁂
When he dies she remembers his promise. She remembers how much more timid she'd been then, desperate for a friend.
But still, she cries for him in earnest. Not in public, though. Her grief is so close to her heart and only hers that she can't bear to tell anyone about it, even Annabeth.
It pains her. She knows that he's the only one who can ease her pain.
So when she visits his grave she brings him daffodils because he'd told her they were his favorite, and she whispers to the coffin:
"Family."