For Science

Everything was set up perfectly.

Izzy reviewed her seemingly too short list of for her current experiment. Testing the five senses was the obvious route. Then came the other senses she had recently learned about. One that she was most excited to test was proprioception. Could having a parabatai really help Alec be more coordinated? Dad said it was a growth spurt that he had gone through too and just meant that Alec would need to train more to adjust. She devised to test that sense through a series of balance and reflex exercises. The main thing was to not let either one of the parabatai know they were being tested.

Jace and Alec would be back from their mission any minute now. Hopefully, they had encountered something to activate the battle bond but weren’t harmed. She had seen it in action only once before. The two were training together and for a few brief moments everything about them appeared nearly choreographed. A combination of fluidly graceful and deadly accurate motions that captivated you. It truly was like watching Heaven’s angelic vengeance in human form.

Hodge had been very pleased so kept them late, trying to narrow down what had activated their parabatai bond. It was second nature now for Jace and Alec to open the bond if needed on a hunt. Lately though it seemed like they would almost sink into the bond subconsciously.

Izzy had asked Hodge about it after she caught them walking in step together. Multiple times. Another time they’re hands shifted as if mirroring each other. That had been the catalyst for this experiment.

Izzy was pulled from the musings by a familiar bang from the weapon’s room, followed by Alec’s unmistakable curse. He must have misjudged the length of his new bow again. Alec was a creature of habit, recently giving both her and Jace endless amusement.

She entered the hallway silently thanks to her freshly activated soundless rune. Jace’s laughter echoed towards her, “At least it wasn’t your head this time!”

“Shut up.”

Izzy couldn’t help defending Alec in this. Jace had years of towering over the Lightwood siblings. “At the current rate of this growth spurt, he’ll be taller than you are soon.” As she had hoped, both Jace and Alec’s head snapped up at her unexpected presence. Perfectly synchronized.

Quickly assessing the lack of ichor on Alec’s gear, Izzy fitted herself under his chin and curled her arms around her big brother. “Good fight?”

Jace didn’t miss her implications. “We’re okay, Izzy.”

She scrutinized Jace. Patches of ichor burned skin glowed an angry red from under the small tears in his gear. He was focused on thoroughly cleaning his blades but even when finished wouldn’t make a fuss about the marks.

“Really, Izzy. We’re fine.” Alec’s arms tightened around her.

She sunk into his embrace. Until pain scorched up her bicep. Hissing, she moved to assess the damage to her arm and halter top.

Jace and Alec’s was reaction in instantaneous. The parabatai firmly cradled her now faintly ichor burned arm in their hands. Alec’s eyes were filled with guilt while Jace’s expression promised revenge on whatever had caused her distress. Their words flowing over one another’s, yet still somehow remaining coherent.

“I’m so sorry.”

“Izzy, what hurts?”

“By the Angel, are you okay?”

Their voices were echoes of protective concern. It stuck her then how fast they had both moved. And without Alec’s recently developed clumpishness or Jace’s inherent aversion to touch. The gentle tenderness that Jace used to wipe the ichor from her arm was so…Alec. The hasty but perfectly confident way Alec drew an iratze near the resulting pink skin was so…Jace. Their bodies overrode what was instinctual behaviors just to accomplish whatever was considered a ‘dire’ task.

Her eyes widened with dawning realization at just how deep a parabatai bond could go.

Jace let go of her first, glaring as he twisted Alec’s willing form around, annoyance lacing his voice, “There’s ichor on your back.” He began scrubbing the spot like it daring to exist, let alone potentially hurt his parabatai, had personally offended him.

Laughter bubbled up from Izzy at how quickly her ‘crises’ was a thing of the past as now there was a possibility that Alec was injured.

“It’s just on my gear, Jace, it’s fine.” Alec rolled his eyes, then returned his attention to his sister. “What you been up to tonight?”

“Studying.” Izzy attempted a nonchalant shrug at the half truth, “I’ve got a theory I want to test out.”

“Really? What on?” Jace’s head popped up from behind Alec.

Two uncannily similar expression of interested curiosity focused on her.

“Umm…” This was going to be harder than she thought. Her experiment didn’t touch on nearly enough to be considered substantial evidence to support any results she’d found so far. Squaring her shoulders, Izzy excitedly resolved that it was at least somewhere to start. Additional experiments could be conducted later. “I can reveal my hypothesis once I have collected and analyzed more data.”

Jace looked confused by Izzy’s unusually vague answer but dropped it. He went back to the table to finish cleaning his weapons. Her enthusiasm couldn’t be hidden from Alec though, causing him to glare suspiciously at her. “What kind of data?”

With a sly grin, Izzy slipped past him and into the hallway. “It’s a secret.”