This is set in COLS, so if you have not read it yet, RUN AWAY. AND READ IT. This is a fanfic with Jace and Sebastian, and in the next chapter, this story will reek of lemons.
Jace woke up in a strange bed, somewhere he had never been before. He felt a warm body next to him. Clary, he thought. He turned over, spooning her. He put his hand on her arm, but it felt unusually hairy. He looked up, seeing a head of long blonde hair. But Clary's a redhead, he thought to himself. Then he put the pieces together. By the Angel, I slept with Sebastian. He spasmed, pushing himself away from Sebastion's sleeping body, and cried out before falling off the king-sized bed. Sebastian bolted upright, a knife in hand as he looked at Jace's body on the floor. "What's wrong?" Sebastian yelled.
"What's wrong?" Jace mocked, "What's wrong is that I just woke up in bed with the satanic fiend that murdered my little brother and countless others. And that satanic fiend is supposed to be dead."
Sebastian looked mildly amused. "It's actually demonic, not satanic. And you forget the fact that you're supposed to be dead too."
Jace gritted his teeth. He was right. "Hm," said Sebastian. "The rune that binds us should make you a bit less hateful. Show me your chest."
Jace backed against the wall. "You know what, I think I will. And then, I'll jump onto my rainbow-farting unicorn and fly off into the sunset."
"Just because we slept with each other doesn't mean you have to be such a bitch." Sebastian jumped down from the bed, gliding to Jace. Jace would move away, but again, he was against a wall. Sebastian put both hands on the neck of Jace's shirt and tore it down the middle. The sinister rune was still on Jace's chest, directly above his heart, but a giant slash cut the rune into two pieces. "Ah, so that's why you're so moody." Sebastian grabbed a stele from a drawer of the nightstand. "A simple iratze should fix that."
Sebastian began drawing an iratze with the stele, when Jace began to struggle. "Get away from me, you sick bastard!" Jace sent a kick Sebastian's way, which connected with Sebastian's knee. Sebastian dropped the stele, clutching his knee, and Jace began to run. Sebastian tried to stand up to pursue, but his knee buckled as soon as he put pressure on it. Sebastian collapsed to the ground, but he wouldn't let Jace get away. He wrapped his hand around Jace's ankle, causing Jace to fall to the floor. "Let me go!" Jace yelled, as Sebastian twisted Jace's ankle as he dragged him across the hardwood floor. Jace gritted his teeth as his ankle burned with pain.
Once Jace was close enough, Sebastian sent a powerful right hook to Jace's jaw, watching his eyes roll back into his head as he collapsed. Sebastian finished the iratze that overlapped with the crude rune over Jace's heart. You're my bitch now, Herondale.