How the pinky hooking gesture came to be. Takes place after Clockwork Prince.
"Jem, beside Tessam hooked his smallest finger through hers.
It was a habitual affectionate gesture,one that Tessa had grown used to over the past months,
enough that she sometimes put out her hand without thinking, when he was standing by her."
They all had opted to attend the next regular Clave meeting, although it was something that was generally only attended by Charlotte and Henry, given that, as Will put it, "the entire meeting was populated by pompous political ninnies." Charlotte had laughed aloud when he'd said it in the carriage, a strange experience for everyone in attendance, for they were all used to Charlotte chastising Will. When she'd regained enough composure to attempt to correct his behavior, he'd given her a winning smile and apologized, she'd very nearly choked on her words. It was another glimpse of the real Will, the one who loved and needed love in return and allowed himself to show it and the familial-type exchange had nearly brought Charlotte to tears.
But, pompous politicians or not, the entirity of the inhabitants of the London Institute had opted to go with them and had lined the front row of the chambers a full thirty minutes before the meeting was actually due to begin. Charlotte had said it was supposed to be a short meeting. There was no new news of Mortmain and Cecily's request to become a Shadowhunter had been a mere matter of paperwork. She didn't expect there to be many in attendance and hoped that it would be a good time for Jem to request permission to marry Tessa without causing too much of a ruckus.
Tessa, however, had only ever been to one Clave meeting before, and, to her eyes, there were a significant number of Shadowhunters in attendance. Not only that, but more had kept coming in as the meeting progressed. Every time the door opened, she sat up a little straighter, ground her teeth a little harder. Jem noticed her nerves from the start but, just as he was considering sweeping her into the Poet's Corner to try to calm her down, the Consul called the meeting to order.
Not being able to do anything else, he'd quickly taken her hand and slipped it into the near nonexistent space between them, linking only their littlest fingers together. To the casual observer, they weren't touching except where the closeness of the front row caused her shoulder to brush his arm. He gave her finger a squeeze, trying to convey his love for her into the small gesture as he stared straight ahead.
I love you, Tessa. I will marry you no matter what. You are my everything and if they tell me no, I am willing to leave them all for you.
The intensity of the thoughts caught him off guard. He had always known he loved her, but he'd never thought of leaving the Shadowhunter world for her. He'd never even considered the matter long enough to warrant that particular train of thought. There were no laws about a Shadowhunter marrying whatever she was; the Clave would see the reason, and that he loved her, that he was dying anyway and they would be allowed to wed, the end. That had always been his reasoning. But now that he has thought these things, he cannot unthink them. He was not eighteen yet, he could still chose to leave them all if he wanted. And he would, if it meant being with her. He would do anything if it meant being with her.
She didn't look at him either, but he saw the tension drain from her shoulders and felt her relax against him as his finger closed around hers. Once again, she had read his mind. It is as if they are already one. The unspoken communication, the assurance of his love, has calmed her frazzled nerves and provided her with confidence. He sees it in now in her posture, the tilt of her chin, and a sudden flash of fierceness in her eyes. If nothing else, they love each other and that will never be taken away from them, the Clave be damned.