Fic written with the following prompt:
'"I will fight for you. I will die for you. I will sacrifice everything I have for you. What else can I give but my entire being?"'
As always, I don't own Harry Potter.
As Bellatrix fled the room, Harry threw himself next to his godfather, crumbled on the ground after being struck by his cousin's curse.
"Sirius!" he whispered as he waved his wand over his godfather, casting the few countercurses he knew as he cursed his lack of attention and focus in school. "Sirius, can you hear me? What did that curse do?"
His godfather chuckled weakly. Harry was barely aware of someone else joining himself and Sirius by the archway, waving their own wand over Sirius and casting spell after spell.
"Something nasty, knowing that bitch," the man mumbled in reply, his eyes slowly losing focus.
"Sirius!" Harry desperately waved his hand in front of his godfather's face. "Why, Sirius? Why did you come?"
The man's eyes cleared slightly as he stared Harry in the face. "You're my godson and my child in all but flesh, Harry. Of course I came."
"But why?" Desperation edged into Harry's voice. "How can you say that when it's because of me you're here dying? I'm not worth it, Sirius!"
His godfather's gaze sharpened. "Never say that! You are worth everything, Harry. Everything."
"But…"
"I will fight for you, Harry." The man's tone held a ferocity Harry had never heard before. "I will die for you. I will sacrifice everything I have for you."
"But Sirius…" Harry whispered, his inner self recoiling from the idea that someone would care for him enough to die on his behalf, rather than caring only for what he could do, or had done, or some silly title that meant nothing but death and loss to him. "You can't, you can't die for me, I'm not worth it…"
Sirius smiled lightly, the moment of clarity fading from his eyes. "You mean everything to me, Harry. All I have left is my love for you, and I will do anything to protect you. With love so deep, what else can I give but my entire being?"
His part said, the man's eyes drifted shut and Harry seized his face, sobbing freely as tears flowed down his face. Sirius' unnatural stillness was the most terrifying thing he had witnessed in his life, and it was only the hope offered by the continued efforts of his unacknowledged companion that stopped him from throwing himself after Lestrange or through the curtain in his unbounded grief.