So this is an idea that I have had for a while. The story is about how one day, when our favorite Shadowhunters are fighting Sebastian, they learn one of Alec's deepest darkest secrets.
This was not a good day for the Shadowhunters of the New York Institute. While on a routine demon hunt, Sebastian had decided to interfere, bringing with him an enormous horde of demons. The children of the Nephilim were encircled and preparing for a fight when Sebastian stepped into the circle. Jace immediately stepped forward, pushing Clary behind him.
"What are you doing here, Sebastian?" he growled out, preparing his blades.
"Now now, don't be too hasty! You see, I was actually searching through the old records of the Clave, when I found something quite interesting. Did you know that your parabatai used to be considered as a prodigy?"
Alec paled dramatically, and the hand holding his bow started shaking. He drew, and shot an arrow at Sebastian, who caught it.
"Really, I laughed when I found out. Alexander Lightwood, the weakest in this pathetic bunch, a prodigy?" Sebastian sneered, twirling the arrow idly, and turned to Alec.
"Why don't you tell them the fascinating story?"
"Why would I want to?" came the quiet reply from Alec, along with a hate filled glare.
"Why wouldn't you want to? The tragic tale of Alexander Lightwood, from child prodigy to disgraceful scum. Besides, if you're not willing to share, then I will."
"Once upon a time, there was a little boy. He started training at a very young age, and showed a lot of talent. His father and mother were very proud of course, and constantly praised him. One day, when the little boy was six, his father took him on a hunt. It was on that day the little boy killed his first demon. After that, he began to go on more and more hunts, and started building a reputation. When the little boy turned ten, the Lightwoods adopted Jonathan Wayland, or Jace. During that first year, Jace was constantly leaving the Institute in secret, and on one of those little trips, he was attacked by a horde of demons. What Jace never knew was that Alec had always followed him in secret, worried about him. Alec arrived at the battle, and immediately shoved Jace out of the way of a demon bite. He and Jace continued to fight, and before long, the two prodigies killed the horde. Immediately, Alexander collapsed. Jace brought him back to the Institute, and a warlock is called. The warlock was able to heal the bite, but the poison had paralyzed Alec's lungs and several organs. Eventually, he healed, but there was permanent damage. Alexander Lightwood could no longer do what he used to, and it appears, switched to archery." Sebastian narrated.
"So,Jace, how does it feel to know that you ruined the entire life of your brother?" Sebastian asked.
"But why can't I remember that?" came the anguished reply from Jace, as he turned to stare at Alec, confusion plain on his face.