Hey all! This is a short one-shot I wrote up after rereading City of Lost Souls and realizing, belatedly, that the copy of A Tale of Two Cities that Jace has in chapter 17 is the same copy that Will gave Tessa in Clockwork Princess. If anyone's interested in cementing my claim, the evidence can be found on pages 385 and 386 of the hardcover copy of CoLS.

Now without further ado: enjoy!

"He unshaded his face after a little while, and spoke steadily. 'Don't be afraid to hear me. Don't shrink from anything I say. I am like one who died young. All my life might have been.'

"'No, Mr. Carton. I am sure that the best part of it might still be; I am sure that you might be much, much worthier of yourself.'"

"Do you remember when you read this to me in Paris?" Clary asked, snuggling closer into her boyfriend's side. "It was the exact same passage."

"You know, as much as I want to forget Paris – and Shanghai, and Venice, and Prague, and everywhere else – that is one thing I don't want to lose." Jace put his arm around Clary's shoulders and pulled her in close. She reveled in his warmth, feeling the ever-present but contained fire burning inside him.

Clary happened to glance at the old, worn copy of A Tale of Two Cities in Jace's hand. Again she saw the end of the faded dedication: With hope at last, Will Herondale.

"Do you ever wonder?" she asked the Herondale next to her.

"Hmm?" Jace replied, distracted by her curls. "Wonder what?"

She flinched away as his fingers approached a ticklish spot behind her ear. "Who Will Herondale was," she clarified.

His fingers stilled. "Why?"

She turned onto her side so she faced him. "Well, you never knew Stephen or Celine," she began. "And even though you act like you don't care, I know that you know that you want to learn about your ancestry. Don't try to deny it," she added when Jace opened his mouth. "Anyway, I was looking through the books in the Institute library and found a book on Shadowhunter family history. I read through it and found this."

Clary reached into her art bag – which she'd always used strictly for art, save for her stele in her colored pencil case – and pulled out a crisp folder. From it she pulled a sheaf of papers.

Jace stared at her. "You researched the Herondale family?"

She gave him a defensive look. "What? I was curious."

Clary got off Jace's bed and went to his perfectly-organized desk. She laid the papers out and gestured for him to come.

"Look," she said, pointing to one page. "The book I found only went back as far as 1835. There was a man named Edmund Herondale, who left the Clave to marry a mundane named Linette Owens. They had three kids: Ella, William, and Cecily.

"According to the records, Ella died at age 14; her brother William left soon after for the London Institute. He was twelve. Five years later Cecily followed him. But see? That William is the William in the dedication. It has to be; that's the only William in the Herondale family. So that's who the book belonged to. At least, it did before he gave it away."

Jace was silent. When Clary glanced at his face, she was startled to see his eyes glistening. He sat down heavily in the desk chair, and she placed a hand on his shoulder.

"Jace? Are you okay?" Clary reached out and began to gather the papers. "I'm sorry, I shouldn't have gone behind your back. This is personal, and I know you think of yourself as a Lightwood –"

A hand landed on the pages, stopping her rushed collection. She looked into Jace's eyes.

"Thank you," he said. "I know I said I didn't care about the Herondales, that my family is the Lightwoods. But this means more to me than you can understand."

Clary just nodded. "Of course."

Jace nodded as well and then turned back to the papers on the desk. "So. Where did the Herondales go after William and Cecily?"

Clary smiled. "Will married a girl named Tessa Gray. I can't find her date-of-death or her affiliation with Shadowhunters anywhere. Anyway, they had two children, James and Lucie. James married Cordelia Carstairs, and Lucie married Jesse Blackthorn. I can't find any children of Lucie and Jesse, but James and Cordelia had Owen, who married Lydia Kingsmill.

"Marcus was the son of Owen and Lydia. He married Imogen Whitelaw, who became your grandmother. They had your father Stephen, he married Amatis, got divorced, and married Celine. Then there's you and that's that."

Jace frowned. "What happened to Cecily?"

Clary shuffled through her notes. "Cecily married Gabriel Lightwood. They had three children: Anna, Christopher, and Alexander. Christopher married Grace Cartwright, and they had a son named Isidore. He married Catia Monteverde. They had a son named Andrew, who married Phoebe Gladstone. Those two had Robert, who married Maryse and had Alec, Isabelle, and Max. And adopted you, which I'm not sure would've happened if they'd realized how much of a handful you'd turn out to be."

Jace let out a startled laugh. "I'm a handful? Clary, you run into trouble almost everywhere you go, and you don't take even a second to consider your own wellbeing. I'm surprised your mother hasn't put a tracking rune on you yet." Something occurred to him. "Does Jocelyn know you're here?"

Clary winced internally. "I'm sure she's realized by now."

"Clary!" But Jace was laughing. He shook his head slowly. "What am I going to do with you, Clarissa Fairchild?"

Clary pretended to think. "I don't know," she shrugged. "Maybe you could go back to the library with me to research the Fairchild family? I want to know about my ancestors, too."

Jace leaned in close. "Well let's go, then."

Clary turned to open the door but was stopped again by Jace's hand on her arm.

"Hey," he said, looking down into her eyes. "Thank you, Clary. Really. You have no idea how long I've wanted to know where I come from; I was just too scared to do it myself."

"Of course," Clary said again. "There's no need to thank me; I'd do anything for you."

"I know." Jace smiled. "Angel, but I love you."

"I love you, too."

As their lips touched, Clary's mind went blank. She was just about to suggest they sit down so he didn't have to bend when she felt Jace smile against her mouth.

"Let's not keep the Fairchild family history waiting, shall we?" he whispered low in her ear. He pulled away and chuckled at her dazed expression.

Clary shook herself out of her shock. "You're evil, Jace Herondale." Her eyes widened. "I'm sorry, I meant to say –"

Jace shook his head. "Wayland, Morgenstern, Herondale, Lightwood…. I don't care what I am as long as someday you'll agree to share the same name."

Clary blinked up at him. "Huh?"

He smiled. "Don't worry, that's not a marriage proposal. With everything going on, and with your mother and Luke getting hitched in a couple weeks, I think one wedding is all anyone can handle. But don't despair." He winked. "I still plan to be drawing that rune on you some day."

He opened the door and stood back for her to exit.

Yay, I did it! I wrote a crossover!

For those who don't know, I've only ever had one crossover story, and I deleted it because it started confusing me. This may be the start of many crossovers to come!

All information about both the Herondale and Lightwood families came from the Shadowhunter Wiki. If anyone is interested in the Fairchild family, or Gideon and Sophie's side of the Lightwood family, let me know.

If you liked it, please review. If you didn't like it, I love constructive criticism! (Please no flames!) Let me know what you thought/think, and I will (hopefully) see you all at my next one-shot/chapter.