Cassandra Clare said this quote

All my life, since I came to the institute, you were the mirror of my soul. I saw the good in me in you. In your eyes alone I found grace, When you are gone from me, who will see me like that? There was a silence then, Jem stood as still as a statue. With his gaze WIll searched for, and found, the parabatai rune on Jem's shoulder; like is own, it had faded to a pale white. At last Jem spoke. The cool remoteness had left his voice. Will breathed in hard, remembering how much that voice had shaped the years of his growing up, its steady kindness a lighthouse beacon in the dark. Have faith in yourself. You can be your own mirror.