Burning Bright Right Till the End, by Mia_Zeklos

It was exactly like Jace had imagined it. The parabatai bond was the most intimate and yet the most unobtrusive thing he’d ever felt. It pulsed under his skin like a second heart; like his soul had moved a little to the side to make place for Alec’s and it was fascinating in ways Jace had never thought of.

Teen, Jace POV. This is gorgeous, going from Jace’s arrival at the Institute to the end of season 1.