UPDATE 11/18/15: Now includes canon introduced in Angels Twice Descending.

DISCLAIMER: I do not own, though my Cassandra-level evilness may cause some confusion. I used the line "There are things our souls want, and mine wants you" from City of Heavenly Fire and therefore I do not own that, either.

When it first started happening, Simon tried to brush it off. In the back of his mind, though, he knew things were bad if Isabelle had a memory rune on her ribcage.

Finally, though, Becca and Max teamed up and made him take her to see a mundane doctor, not the Silent Brothers. They confirmed his fear: Isabelle had developed dementia. Catarina had said that her memory rune must have helped to keep it at bay, but was now incredibly weak from working overtime, causing everything to bleed through, and she also said that it was unlikely any mundane medications would work.

Simon broke down once she was asleep.

Their daughter, Olivia, was now in charge of the New York Institute. She had invited everyone over for Christmas morning, which meant a lot of people at once, but apparently it was her turn to host, and it was the Institute, after all.. Simon and Isabelle had taken the same van that they had had for seventy years. Well, not the exact same one, not really. Becky's husband had somehow managed to keep the van itself, but give it a new engine a while ago. Simon didn't know what would happen to the van now that his brother-in-law was dead.

"I think it's official: We need a new car," Isabelle laughed when she climbed into the front seat and the seatbelt wouldn't work.

"Well, what exactly do we do with this one? I don't think anyone would want to buy a van covered in your brother's blood and demon gunk and Becca's placenta and Diet Coke-" Simon laughed.

"Shut up."

"Maybe you should drive. I'd rather risk not having a seat belt over you."

"I don't think it's good for me to be driving. I could forget what I'm doing at the wheel."

This was Isabelle, who had denied an attraction to him for months. She was great at hiding everything from everyone. She could accept the diagnosis with grace, make jokes about it, pretend it was alright.

But he knew her, after all the years they'd been together. She would let him in eventually.

They rode to the Institute in silence, parking a block or so away. Isabelle grabbed the sack of presents out of the back and almost fell over due to the sheer amount of items in them.

"You got it?"

"I better," she laughed. He planted a kiss to her cheek and made his way up to the front gates to open them for her.

"Simon, what're you doing?" She sounded so lost and confused, and Simon froze. Turning around slowly, he asked, "Isabelle, what do you mean?"

"You can't go inside the Institute. You're a vampire." Simon looked down at his wrinkled yet Marked hand and tried not to cry.

"I'm a Shadowhunter now, remember? And we're married, with three children, and they're grandparents themselves. Luke is even a great-grandfather. Remember?" He thought he sounded almost hysterical, but she didn't seem to notice. She was staring at him like he was speaking gibberish.

"What?" Isabelle asked innocently as she snapped out of it, "C'mon, Si, hurry up; Liv will kill us if we're late."

"I'm right behind you!" Simon called behind her as she made her way through the gates and up the steps, looking like she was twenty again with the grace and poise she carried.

He tried not to cry as he made his way inside.

"What's this for?" Clary asked as Simon randomly pulled her into a hug.

"You were so good with me, back when I lost my memories. I didn't give you enough credit."

"Si-"

"You can't tell me that this is that different. Yes, the circumstances of the fading memories are, but you were in the exact same position that I am now. You had all these memories of me that I didn't have of you."

"Simon?" she said worriedly, because she could tell that he wasn't finished with his train of thought, even if he really wanted to be.

"Except mine came back, and I wasn't under a death sentence, unless you count Ascension as one. So maybe it is a tad different."

She wrapped her arms around him tightly.

"Dad?" Luke called, peeking his head in, "She wants to see you."

Clary's arms dropped from Simon's body and he followed his son to his wife's bed. Izzy was silent, staring almost blankly at the wall.

"Why don't we step out for a minute, Dad, Luke?" Sarah said, tugging on Jace and then Luke until both boys had left the room.

"Did I love you?" she asked quietly.

"Not right away. And when you started to, you pretended not to. But we got our act together, and shortly after our engagement, you got pregnant."

"How many children did we have again?"

"Three. Becca and the twins, Olivia and Luke."

"Was I a good mother?" she asked. Simon felt tears stinging at his eyes.

"You were the best, even if your cooking was dismal. Still are the best, but don't let Clary hear me say that." She chuckled, taking his hand in her own.

"I'm not much good now. They're all grown up, aren't they?"

"Yes, they are. But you're still a great mother." She made a 'hmmm' sound, looking out somewhere into the distance. Into what, he wasn't sure. He didn't think he wanted to.

"Was I a good wife?"

"You could've been the worst wife on the history of the planet and I would've loved you anyways," he promised sincerely, pressing a kiss to her fingers.

"I'm lucky I had someone that loved me so much."

"I still do, Izzy. I still do."

"'There are things our souls want, and mine wants you,'" Isabelle said suddenly. Simon choked back a sob. "Did I say that to you, once?"

"Something like that."

Here lies Isabelle Sophia Lightwood

May 19, 1991-November 3, 2083

There are things our souls want, and mine wants you.