Hey! I am writing my first fanfic and I though "no on ever writes anything about Isabelle" so I will! I hope this turns out well, I will want feedback. Let me know what you want to happen during the story and If I like it, I will put it in the story. I own nothing but the plot, everything else goes to the fantastic Cassandra Clare!

Chapter 1

Ever since the day Isabelle Lightwood's mother, Maryse, told her that her father, Robert, had cheated on her mother, she wondered if her mother had been completely faithful as well. The past couple of months were too busy for her to think too hardly on this, but now that Simon is in Idris in the Shadowhunter Academy and Sebastian is dead, she has a lot of time on her hands. Alec isn't even at the institute all that often, he is always with Magnus.

Clary moved in, to extend her training is what she told Jocelyn, but Isabelle suspected that is was to be around Jace more. The institute seemed so much more empty than it had before. Alec is gone. Robert is gone. Max is...gone. Maryse has pulled slightly away from the family after her and Robert decided to end their marriage. She believes it has also to do with the fact that Max is gone as well.

What if Maryse wasn't faithful to Robert? Alec is obviously their son. He looks like them and has blue eyes like Robert. Max looked like them as well with grey eyes, which is a variation of blue. People always said that Isabelle looked like Maryse, except her eyes. Isabelle had dark brown eyes, so dark they are almost black. Where did they come from?

Just then there was a knock on the door, pulling Isabelle from her thoughts. She slid off the bed and walked to the door. There in the hallway stood Clary Fray, the only mundane she actually liked. The only thing was that Isabelle didn't consider her a mundie anymore. She has proved herself over and again that she is strong like any Shadowhunter.

"What's up, Clary?"

"Well, Jace went with Alec and Magnus for a while and I was wondering if there was anything you would like to do?"

"Well, I do kinda want to talk to someone about something, and I trust you. Come in here." Isabelle opened the door wider to let Clary pass her, then shut the door.

They walked over the the pink, soft, fluffy bed and sat. Clary didn't know what to think. Isabelle seemed so cautious and mysterious, and she never seems this unsure about anything. She had a far off look on her face, like she was lost in the Land of Isabelle.

"What's the matter, Izzy?"

"Well, have you ever noticed that I have different eyes than both of my brothers?"

"Well, I guess, but what does it matter? Lots of people have different eyes than their parents, where are you going with this?" Clary looked completely confused. What is she getting so upset about?

"I mean, what if dad wast the only one who cheated? What if mom cheated once or twice before before dad did? I don't know when dad's affair started, but what if mom cheated too, and got pregnant? Then passed me off as dad's kid, and decided never to take that chance again? So Max was dads, Alec is for sure dads, but what if I'm not?" Isabelle had a look of pure distress all over. The way she was sitting wasn't the confident Izzy that Clary had grown used to over the past months. This one looked slightly broken and very confused.

"I don't know if that is really any room to accuse your mom of that. And anyway, everyone knows that Robert and Maryse are your parents. It's like the way you guys took Jace in as your brother, everyone knew that you all loved him, so he was your brother. It's the same, everyone knows that Robert and Maryse love you, and they have no room to even think that Robert isn't your father."

Isabelle's mood seemed to lighten a little. But not much. "Okay, I guess you have a point."

Another knock on the door. Who is it now? Isabelle opens the door to see Jace.

"I thought you were with Alec."

"I was. And now I'm back. Clary and I had plans for the evening, so I came to collect her."

"How did you know where I was?" Clary looked slightly baffled, but was smiling at Jace. She had a look of pure admiration in her eyes. Isabelle wondered if that was how she looked when looking at Simon. She almost hoped not. But she loved Simon, so it didn't really matter.

"Well, no one else is even here, so I came to where my beautiful sister and irresistible girlfriend were probably congregated. And look, here they are!"

"Let's go." Clary said, jumping from the bed. She kissed Jace on the cheek and they both left Isabelle to her thoughts.

She still didn't completely believe that she was absolutely her fathers child, but how would she find out?

So how was the first chapter? I hope it was ok. Let me know if you want to see something happen in the story and if I like it, it will happen! Review please! I don't know when I will be able to update for sure. I don't have internet. So I will write and update when I get wifi. Let me know what you think.

Until next time.