“Faith,” said Jem. “That you were better than you thought you were. Forgiveness, that you need not always punish yourself. I always loved you, Will, whatever you did. And now I need you to do for me what I cannot do for myself. For you to be my eyes when I do not have them. For you to be my hands when I cannot use my own. For you to be my heart when mine is done with beating.”

“No,” said Will wildly. “No, no, no. I will not be those things. Your eyes will see, your hands will feel, your heart will continue to beat.”

“But if not, Will-”

“If I could tear myself in half, I would-that half of me might remain with you and half follow Tessa-”

“Half of you would be no good to either of us,” said Jem. “There is no other I could trust to go after her, no other who would give of his own life, as I would, to save hers. I would have asked you to undertake this mission even if I had not known your feelings, but being certain that you love her as I do- Will, I trust you above all, and believe in you above all, knowing that as always your heart is twinned with mine in this matter. Wo men shi jie bai xiong di-we are more than brothers, Will. Undertake this journey, and you undertake it not for yourself alone but for both of us.”

“I cannot leave you to face death alone,” Will whispered, but he knew he was beaten; the sands of his will had run out.

Jem touched the parabatai rune on his shoulder, through the thin material of his nightshirt. “I am not alone,” he said. “Wherever we are, we are as one.”

—  Cassandra Clare
Clockwork Princess