He's kneeling as the dust settles, waiting for the shock of pain that follows after a wave of adrenaline wears off.
It doesn't come.
Perhaps she'd been weaker than she thought she was, when she'd tried to cast the spell. Or perhaps she'd been lying from the beginning and hoped that he'd believe her. He doesn't know. The reasons don't matter now.
And Subaru is reaching up, cradles his face in his hands. "Thank you," he gasps. There is joy in his smile, and his eyes are glazed and wet. "This is all I ever wished for." He holds Seishirou's gaze for a breath. Then the light slips away and he falls, lifeless, down into his arms.
His hands tremble when he dies. He's more than empty now, he is hollow. There's a void where none used to be, and he wonders if this could be what it means to miss someone.
"You'll have to trust me," the girl had said once, as the sakuras fell down around them, "and I'll have to trust you." That blue age ago, he'd scoffed.