Toadpaw tries to fix her, he does. His sister is a mad one- is he the only one to see it? He catches her one day, skinning a minnow alive as it thrashes in claws streaked silver.
"Morningpaw," he says, and she looks up, scowling.
"Don't talk to me," she snaps. He knows he's not supposed to, but his golden sister has a heart of shadows. He just wants to help.
He will see that there's no way to mend Morningpaw. This realisation takes a long time to come to him. She grows wilder and wilder, but he's sure it's not irreversible. Just like his sister, the concept of permanent is a theory to him. He dies while raiding the city, the first casualty in years. And as he fades, he thinks he sees just the slimmest flash of gold, and perhaps she whispers goodbye, or maybe his mind is deluding him, because he failed her.