" You swore to stay with me,” he said. “When we made our oath, as parabatai. Our souls are knit. We are one person, James.”
“We are two people,” said Jem.
“Two people with a covenant between us.”
Will knew he sounded like a child, but he could not help it.
“A covenant that says you must not go where I cannot come with you.”
“Until death,” Jem replied gently.
“Those are the words of the oath. ‘Until
aught but death part thee and me.’ Someday, Will, I will go where none can
follow me, and I think it will be sooner rather than later. "
― Cassandra Clare , Clockwork Prince (The Infernal Devices, #2)