Simon had survived the blast somehow, the Adamas stone in the walls of the Institute absorbing the heavenly energy, making them stronger and preventing the light from killing every Downworlder in Manhattan.
But when Alec reached the centre of the carnage, Jace and Serena were gone. Clary had explained how she didn't do this and that Jace did, and Alec ran to find Magnus and/or Serena, hoping his wife had done as she promised she would and used her Portal Pendant.
Serena wasn't with Magnus though. She was with Jace outside the Institute, stopping Valentine from killing Luke.
He had been about to bring the Soul-Sword down on the wounded alpha when Serena and Jace brought their swords out to block it, pushing Valentine away.
The man managed to disarm Jace, holding his back to his chest and the Soul Sword to his throat as Serena threw down her sword, not going to risk her brother's safety as she quickly handed Luke her jacket to cover himself with, him using the sleeve to press down on his wound and try and stop the bleeding enough for his werewolf healing to kick in.
"You told me I had demon blood! Why?" Jace asked as he tried to fight Valentine's grip, but the man held him fast.
Valentine met Serena's eyes.
"Because that's how the both of you are. Always ready to right the wrong, to stand up to those who can't stand up for themselves, Serena especially. A real-life hero."
"So, you used us? Used Jace?" Serena questioned.
"I just made sure Dot overheard me. That's why I left her behind so you would come and save the day," he answered and Jace fought, Serena taking an anxious step forward, before Valentine's gaze pinned her.
"And I activate the sword instead," Jace spat. "You lied. It was never demon blood. I was always like Serena."
Valentine smiled. "I couldn't very well say Serena had demon blood. That truly would've been absurd. But you two are my greatest achievements. I'll admit, the both of you took me by surprise, but you are."
"We're not your achievements! We're your children!" Jace said heartbrokenly, and it reminded Serena of how he used to try and please Michael. Funny how Michael ended up being Valentine.
"He's not our father, Jace," Serena piped up after reading the look on Valentine's face. "That's why Jocelyn didn't remember me or have anything of mine. I was never her daughter."
"I am not your father," Valentine confirmed, looking to the both of them, Jace unable to see him with the sword at his neck. "I took Jocelyn's memories of her first pregnancy in hope that she would forget about my experiments. She is not your mother, I am not your father. And Clary is not your sister."
"More lies!" Jace growled, sword drawing blood from his neck as he struggled.
"Don't I wish," Valentine said. "Truth sword, remember?"
And Jace stilled from shock.
Serena had heard all she needed.
And while his attention was on Jace, she pulled a throwing knife from her pocket and wedged it in Valentine's shoulder, the man letting Jace go in the process as she scooped up her sword and tossed it to her twin as she picked up his.
They dodged and swiped at Valentine and eventually, as the twins moved in perfect unison, Serena was able to kick the Soul-Sword from his hand.
As the trio fought, they didn't see Clary as she picked up the Soul-Sword and drew a rune on it, deactivating its' heavenly power and burning her hand as she dropped it to the ground.
As Clary ran over, Jace had been about to run his sword through Valentine.
"Jace no!" Clary had screamed as Serena reacted faster, kicking her brother in the chest and knocking him to the ground before leaning over Valentine and holding her sword to his throat.
"You are the only one who knows where The Cup is. And that is the only reason why I'm sparing your pathetic life. But mark my words, you are going to pay for every Downworlder that you killed in there and every one that you experimented on. You're going to wish you were dead," she threatened before breaking his nose with a punch for good measure.
"The sword is gone!" Clary yelled and Serena rose, still standing over an unconscious Valentine.
But the sword was nowhere in sight.