Mortal Instruments Fanfiction

Summary: what if Jonathan did not have any demon blood in him, but was an ordinary child raised by one of the most ruthless shadowhunters of all time? How would he react to seeing his little sister for the first time, a sister he never knew he had? Takes place in CoG.

*Disclaimer: I do not own anything.

I can barely recognise myself in the mirror. The white-blonde of my hair that resembles so much of my father seems to have disappeared completely under the dark dye that currently makes my hair black. It's funny how changing just one feature can make a person so unrecognisable. I still have my runes, of course, and the same green eyes –the only thing linking me to my mother.

My mother. I never knew her –not properly, anyway. She left when I was just two years old. She left my father to look after me by himself. I don't know why, and I learnt the hard way not to mention her in front of my father. I guess it's a bitter topic for him. I think he still loves her, in his own way. He could never understand why she'd leave us, why she'd leave him. Over the years, his feelings for her kind of rubbed on me, and now, fifteen years later, I hate her. What kind of mother would leave her own family?

"Jonathan!"

Jolting out of my thoughts, I quickly strap on my weapons belt and run outside. My father never liked to be kept waiting. I find him pacing back and forth in the small living room, muttering under his breath.

"Father?" I said to get his attention.

He looked up, inspecting my disguise. "Not bad," he said. "You don't look like him exactly, but I doubt the Penhallows will notice. They're not a bright family. There's just the matter of your eyes…" His face contorts into one of hatred, the way it always did when he thought of my mother.

"Where is he?" I asked, out of curiosity. "Where is Sebastian Verlac?"

"He's dead," my father said casually. "He wouldn't shut up. Very annoying."

I said nothing. Something was nagging at the back of my mind. It seemed…wrong, somehow. Sebastian was just a boy, fourteen at most. Something I could never understand about my father was how he could kill a person, and move on as if he hadn't just done the worst thing on Earth.

"Whilst in Alicante," my father said, "there's someone I want you to look out for. I need you to act friendly, gain her trust, and then, when the time is right, I want you to bring her here."

A girl? My father wants me to befriend a girl? That's a first. Usually my father would get me to fight the demons that he summons with the Mortal Sword he had acquired from the Silent City in New York –just as extra training. If my father wanted me to gain a girl's trust, she must be really special.

"Who is this girl?" I asked, shouldering my bag.

He looked straight into my eyes and a grin spread across his face.

"Her name is Clarissa," he said. "Clarissa Morgenstern. Your sister."

*line break*

Somehow the Penhallows believed me when I told them I was Sebastian Verlac, their cousin. But then, I guess they were expecting him –or me. They welcomed me in without any hesitation. Aline Penhallow, a dark-haired girl my age and my supposed cousin, jumped up when she saw and embraced me in a hug. I'd never been hugged before. Such emotional actions were below my father. Nevertheless, I hugged her back, not because I knew her –which of course I didn't –but because I didn't want to blow my cover on the first day. It was all right, I guess. It felt nice to be around people who didn't just ask you to run ten miles or do fifty push ups.

"I'm so glad you're here," Aline exclaimed. "What's France like? I've always wanted to go to France, you know."

At first I was confused, and then I remembered that's where Sebastian Verlac was from. "C'est tres bien," I said in French, grinning. "You should come visit some time."

"If my parents aren't too busy," Aline grumbled. "They're the leaders of the Beijing Institute, so of course they have to keep in touch with the Clave. Sometimes I wish they weren't so important."

"Speaking of Institutes," I said, trying to sound casual. "I heard the Lightwoods are coming here from the New York Institute."

Aline nodded excitedly. "Oh yes. Did you hear what happened? Valentine was there! Apparently he had all these demons under his control but before he could carry out the Ritual, Clarissa Morgenstern stopped him. Can you believe it? Foiled by his own daughter."

I listened in fascination. I hadn't heard this before. But then I guess my father wouldn't have wanted to talk about it. He always hated it when things never went his way. Clarissa Morgenstern. I never even knew I had a sister. Why didn't my father ever mention this to me? Or was this something my mother wanted to hide from us too?

There was a knock on the door and Aline practically bounced over to it. She opened it and let out an excited squeal. She looked back at me.

"Sebastian, the Lightwoods are here!"

Hey, this is my first TMI fanfiction. I recently finished the amazing TMI series, and although Jonathan was evil in the books, he was still my favourite character and I was sad when he died. So this fanfiction is how I think things would have turned out if he wasn't evil. Hope you enjoy this and please review!