A/N: Yet another Will/Tessa one shot. This one was inspired by Cassandra Clare's answers to fan questions as her characters :) It is far shorter than my previous two.
This is dedicated to everyone who reviewed I Never Told You and Bright Lights.

Disclaimer: I am not Cassandra Clare (I only aspire to be as good as her). All characters belong to her. The title belongs to Lifehouse.

There was something dark in him.

Sophie always said that about him to others. He had just heard her say it to the woman they hired to replace Agatha (and whom he had already snapped at twice) as he made his way from the weapons room to the library. He heard her say it in the same tone of foreboding as he had heard her say it to many others before.

There was something dark in him.

What worried him was not that such was the light in which others, perhaps with the exception of Tessa and Jem, saw him. No, what mortified him the most was that they were right.

He stopped at the doors of the library, considering whether or not to go in. Will confessed himself to be an avid reader, rivaled only by Tessa. Books and weapons were perhaps the only material things he truly enjoyed. It was libraries that he hated. It was the room itself that he had sought to avoid for many years. The books he had read were all from the small collection he kept in his room. Libraries brought back the very memories he fought to push away…

It wasn't until he met Tessa that he frequented the room more and more each day.

Deciding to gather a few books and returning to his room, Will made to open the door but stopped when he heard voices from within. He paused to listen.

"… the Institute with me?" It was Jessamine. Will found it strange that she was in the library. If anyone avoided that room more than he once did it was her.

"I have thought about it, Jessamine," replied a voice Will would recognize anywhere. Of course, Jessamine was there to speak to Tessa. As of late, she had been seeking her company more than normalcy allowed. "But I have yet to decide."

"What is so difficult about making the decision?" Jessamine shot and Will imagined she was scowling.

"I cannot just pack and leave, Jessamine," Tessa replied calmly.

Will felt his heart sink, understanding and horror settling through him. Jessamine had always made it clear that as soon as she was of age she would leave the Institute. Gradually, her many visits to Tessa's room and the many walks they took together made sense. She was trying to take Tessa with her.

"Why not?" Jessamine wanted to know.

There was no reply and for a minute Will thought they might have heard him outside.

"To be frank," Tessa began after the pause. "I… do not know," she paused again and in a quiet voice, so quiet Will almost could not hear it, she said, "I cannot leave, Jessamine."

"You seem to hate it here as much as I do," observed the other.

"I don't hate it here," Tessa assured her without adding anything more.

Jessamine sighed in defeat. "Entertain the notion a bit more, yes?" she asked. It was uncharacteristic for her to ask for anything when she usually demanded it.

"I fail to understand," Tessa began. "You are Nephilim. Why do you want to house a destitute Downworlder that is more trouble than she is worth?"

"Because," Jessamine answered, "like myself, you did not choose the existence you are forced to live in. And also, I know the feeling of desperately wanting an escape." Before Tessa could reply, she added, "Besides, I never fully adopted Shadowhunter customs, much less their prejudices."

Will heard her rise and immediately hid around a corner nearby. Jessamine exited the library, took a moment to fix her hair before a mirror in the hall, and with a sigh she vanished in the opposite direction of the hall.

He knew very well that Tessa would remain in the library for at least a couple of hours. The proper thing to do would be to walk away and lock himself away in any other room but the one she inhabited, out of her sight and thus out her mind. He could go back to avoiding her and perhaps one day she would indeed leave and he would never see her again…That would be the proper thing to do. But William Herondale had yet to do a proper thing in his life.

The thought of her leaving and the uncertainty of what her decision would be were gnawing at him like demons trying to escape a dimension. He had to know.

Without another thought he walked inside. Tessa did not hear him enter for he was trained to be silent and she was occupied examining the titles on the shelves. It was the sound of the doors closing behind him that made her turn abruptly.

Brief shock colored her face at seeing him standing there but she otherwise said noting. She stood very still, watching him, the surprise slowly dwindling into confusion. Will had expected her to be angry. In fact, when he considered everything he said to her, he decided she should be furious.

But it was Tessa after all and the manner in which her mind operated was far more unpredictable and wonderful than anything he could imagine and it still managed to surprise him. Of course she was not angry. She was far too benevolent and perhaps too hurt by the resilient cruelty of his words to harbor the feeling.

They both remained very still, Tessa with a dusty, old book in her hand and Will with his hands on the cold doorknob behind him. Finally, when the silence proved too much for Tessa to bear, she muttered, "I would not want to be a bother. I will just take these books and leave." Swiftly, she walked to the large, mahogany desk where a small box filled to the rim with books rested. Will realized that very much like him, Tessa too stocked up on books so as to avoid meeting him there.

"Leave? Is that what you do in every situation? You just leave?" he asked, the words coming on their on accord. The bitterness that dripped from his tone was unmistakable as was the resentment.

Her lovely face grew more puzzled. "Pardon me?"

"I heard what you told Jessamine about leaving," he could see understanding cross her face instantly followed by indignation, most likely at his eavesdropping. Before she could say anything, however, he went on, "You stupid girl!"

"What?" she retorted, offended.

His hands had long left the brass doorknobs and in his state of fury, he began to pace. "Stupid, stupid, stupid," he said once more. "Do you not understand the danger you are putting yourself in if you leave?" He said each word slowly, angry, terrified and desperate for her to understand that she simply could not leave. "Has it crossed your brilliant mind that Mortmain could have already figured out you are not really dead? He would have you trapped the minute you leave the Institute grounds."

Tessa was paler than usual, her eyes were bright and her lips were pressed into a hard line. Now she was furious.

"Has it crossed your brilliant mind," she started quite furiously, "that that is exactly why I have not left?" She spoke with a tranquility that did not match her angry expression. "Why do you think I have not answered Jessamine's request? Or gone back to America?"

The disappointment he felt did not surprise him. He, however, pushed it down and said, "Mortmain. Is that why?"

"Yes! Why else would I be here?"

In the silence that elapsed, they looked—really looked— at each other, taking in one another's expressions. Will knew that the traitorous silence revealed it all, or perhaps it was written on his face for her to read (as she always did). It said of how half of him knew she only stayed behind for her safety and how the other half of him wished he would be the reason she had not gone.

Tessa finally ripped her eyes away from him and instead invested her attention on the book box before her, rearranging the many titles inside. "As far as I know," she began quietly just when Will thought she would no longer speak. "There is no other reason for me to stay."

He wished he could tell her he regretted that day on the rooftop, that what he said was unnecessary and irrelevant. But he found himself incapable of lying to her. Because he did not regret it. What he did regret was what he was. He regretted what happened when he was younger. He regretted that none of it was Tessa's fault and yet it hurt her, too.

"Do you regret it, Will?"

He froze, taken aback by the question. It was as if she could see right through him. At times he thought she really could. But that was impossible because if she could then she would understand everything…

Careful to keep his cool demeanor in place, he asked, "What do you mean?"

"Kissing me," she whispered.

In that moment, as Tessa looked at him expectantly with bright, gray eyes, Will wished for many things. He wished he would have walked away moments before so as to never answer this question. He wished he was not damned and condemned to spend his life burning in the Hell that he created so many years ago. But most importantly he wished with every fiber in his being that he was the William Herondale he was before he opened that godforsaken box. He would be different today—better, good.

Perhaps it was that William Herondale who Tessa deserved. His former self would have loved her properly. He would be able to hold her and kiss her whenever he pleased. He would be rash and insane enough (because, of course, it was still Will) to damn it all and run away with her…keep her safe…make her happy…and maybe, if by some miracle she agreed, one day marry her.

But he was not that person, no matter how desperately he wanted it.

There was something dark in him.

In the lamplight, Tessa looked as she always did: pale and lovely. But the glint in her eyes when she saw him was, for the most part, gone. It was replaced with fear, pain, and loss—most because of all the horrid things she had learned about her existence and the others evoked by him and no one else. She was like a porcelain doll, given to a careless child to mercilessly batter and break.

Tessa waited for his answer and it killed him to see there was hope in the way she looked at him. Hope. If years of fighting had taught him anything it was that there was nothing to stop him from killing something that was already as good as dead.

"Yes, I regret it," he answered, his voice sounded far away to his ears. "It was a mistake."

There was a pause.

"And those things you said?"

"No, I do not regret that," he said. "It was necessary."

Tessa closed her eyes tight. She would never allow him to see how shaken she really was by his revelation. Yet he could see it in the way her hands gripped her dress at her sides or in the way her breath shook when she sighed. Without another glance, word, or anything, Tessa took the box of books in her arms and made her way toward him— no, he corrected in his mind, toward the door.

Will stepped aside to let her go, just like he prepared himself to do, but opening the door with her arms full of books and her heart freshly minced proved too much for her. The box tumbled from her arms and crashed on the floor, spilling the books she would use to try and forget him.

Will was on the floor, gathering them in an instant and stocking them in her box the way she had them.

"Stop," she said quietly, her voice too weak to carry any real command. "I can do it myself." From the way her voice shook, he knew without looking at her that she was starring fixedly at an object in the room to stop herself from crying.

Will paid no heed to her request and continued to pick the books from the floor. He noticed the titles were those Tessa had once confessed to have already read. They were also the ones he admitted to have enjoyed.

"Stop," she repeated, this time much louder. And when he did not, she yelled, "Will, stop! Leave that box alone!"

Her words—words that had been said to him once before—were the trigger.

Suddenly, he was twelve and he stood in a library, one much smaller than the one where he once more had broken Tessa's heart.

Cecily was there, too, looking distraught but very much alive.

"Will, leave that box alone!" she repeated for he did not listen to her first warning. "Father made it clear we were not to touch it."

"But Father won't find out, now will he?" he heard himself say.

"William, no," replied the other sternly, her voice growing in urgency when his hand rested on the lid. "You mustn't! We do not know what exactly is in there."

"I heard Father say something about a demon," he said more to himself than to her. He had heard the stories about his family. He knew of how they were born to fight of demons, to purge them from the Earth. In his very vein ran the blood of an Angelthat was proof enough he had it in him to conquer whatever repugnant demonic traces were contained in that box. In all his years of existence he had only heard about the creatures but never seen one for himself.

"Will, for the last time, no!"

But her warning was lost in the roar that emitted from the box as Will opened it. He had never been truly sure of what exactly occurred next except that it changed his life forever. There were only glimpses and blurs.

The mass of black smoke that shot violently from the confines of the box…the smell of sulfur, death, and blood…The cold that gripped him as whatever was inside the box overpowered him, controlled him…The rage and blood thirst that coursed through his tiny body and that was not his… Cecily's screams, followed by the dreadful silence that would be eternal…all the blood that stained his hands, so much blood…his father breaking through the library doors, gripping him and forcing a cold liquid down his throat…his mother weeping and running to Cecily…her bloody and still body on the library floor…

The sheer and unbridled terror at realizing that whatever overtook him was not fully purged from his body...

Tessa's blood-soaked body in his arms only weeks ago…

All of the images sped through his mind at nauseating speed. They held him prisoner of the heart wrench he felt whenever he remembered, they taunted him, as if to prove once and for all that no matter how hard he tried, he would never get rid of them. They would follow him to the grave and through his descend to Hell.

He was still on the library floor, Tessa's books in hand.

Tessa was still not looking at him, her eyes remained fix on a chair, succeeding in her fight against the tears. "I know that you intentionally force others to think the worst of you," she said at last, unaware of the torment he had just gone through. "I do not know why but the point is that you do it," he could see that it had not been his cruelty that had wounded her but his attempts to disprove something she believed to be true. "I do know, however, that it will take more than false nights of drinking and cryptic answers to convince me you are not, at your core, a good person."

And there it was again: hope, all emitting from Tessa like a shining light. No matter how hard he had tried to kill it once, it would not die. It was stubborn and it burned bright, just like Tessa.

With that, she took the book box in her arms once more and left.

He wished he could share that shred of hope she desperately clung to, that the light would somehow warm him as it did her. But it did not. There was something dark in him and no amount of Tessa's light would pierce through it.

A/N: Thank you if you decide you want to review or add this to your favorites :) Also, on a personal note, this might be the last thing I write in a while since classes start tomorrow! But who knows, I always lie about this.

Now to the fun stuff:

Please don't hate me. I realize Will was being rather cruel but as I said in the opening A/N, it was all inspired by Cassie's answers as him, most especially this one:

Fan question(for Will): do you regret what you did to Tessa at the end of CA?
Will: No.

Here are a few more (I wish I had them all ):

Fan question (for Will): What was your first impression of Tessa?
Will: She hit me. With a pitcher.

Fan question (for Will): If you could tell Cecily one thing, what would it be?"
That I'm sorry.

Fan question (for Will): Will if you could go anywhere in the world where would you go?
Will: Straight to hell.

Question for Will: Will, on what occasion, if any, would you NOT lie?
Will: I wouldn't lie to Cecily.

Question for Tessa: Tessa, what attracted you most about Will?
Tessa: Have you seen him? Besides, he reads the same books as me.

Question for Jem: What's the nicest things Will has ever said to you?
Jem: "I have failed my family before, James, I would not fail you."

FINALLY, in the A/N of my last one shot I mentioned Tessa was in City of Glass and was thus immortal. One of you lovely readers left me a review asking where (I will find your review and personally answer right after this!). Tessa is in page 525 of the American version of City of Glass. For those of you who have any other versions, she is in the Prologue, at Magnus' party. Although she is not mentioned by name, she is the girl he is briefly talking to. And the reason I know it's her is because Cassandra has confirmed it on her site.

If you want to follow her or ask her questions, Cassandra Clare's Twitter is: www(dot)twitter(dot)com/cassieclare

Feel free to leave questions/comments/concerns in the reviews or in a PM

Dang, that was a long A/N! I'll be quiet now :)

Much, much love,


PS. Check this fantastic Will/Tessa video out: www(dot)youtube(dot)com/watch?v=oWbQFsHxgVQ