She screamed, she screamed, she screamed, and all he could do was scream back.
Useless to scream, absolutely useless, he thinks, but he cannot think, cannot think as her bloodcurling screams chase out his thoughts from his distraught head. They bite and tear at his sanity.
He has to block it out, he has to find his thoughts and find a way, he has to save her!
He bellows back at her, screams her name insanely, uselessly, hoping against hope that she'll hear him. He remembers, with a stab of horror, Neville's parents, and he screams again, screams her name louder, hoping that she won't go insane, hoping that she'll hear her name, and perhaps then, if she's already begun to lose perception, to lose a sense of herself, she'll hear her name and remember that she is Hermione, Hermione Jane Granger, the woman who is intelligent and brave and beautiful, the woman whom he—he fully realizes just now—the woman whom he loves...
He hears her speak, and hope shoots through him, she hasn't lost her mind yet, and he hears her shout, "We found it—we found it-- PLEASE!" Again her horrifying scream, and he thrashes wildly and uselessly, like a fool, and he berates himself for it: 'thrashing like an animal, a stupid animal' but what else can he do? He is useless, absolutely useless, and then Luna, who is fumbling blindly with the rope twisted around Harry's hands, tells him to stop, tells him she can't see—
See? And he remembers, he remembers the Deluminator, and with a rush of relief the room is filled with light, and he is slightly comforted by the fact that he is at least not a complete waste, that he can do at least something.
The woman calls her a 'filthy Mudblood' and how dare she? He shouts her name again, and the woman threatens to stab her, to rip her flesh, to penetrate her heart… his blood boils and his heart jumps at the same time; no, she can't die, not here, not now. He doesn't want this to be the end, not when the last image he has of her is of her hair being yanked by Bellatrix, pain and fear dominating her face. He wants his last image of her to be beautiful, he wants it to be wonderful and sweet and everlasting.
He feels the ropes around him fall to the ground, and he has to think, he has to save her, isn't there a way out? He searches the ceiling quickly, but there's nothing, and he mumbles silently, "destination, determination, deliberation," and spins on the spot, but to no avail.
She screams again, and this time he hears the words as that cursed woman shouts them in anger, "CRUCIO!" and he can do nothing. She screams.
His body shakes as he pounds the walls, but he is too horrified to cry, still in utter disbelief, how can this be happening? Dry sobs escape him, his heart rattles in its cage, beating wildly like a dying animal. He hears Harry shout something to his hand, but he can hardly care about that now, now that she is screaming and crying and—he dares to think it— and maybe dying. He pushes that thought out of his head, she can't be dying, the Cruciatus Curse doesn't kill.
She screams again, again, again, and all he can do is scream back but what use is that?!