So Alec turned his head to Jace. Even now with all those conflicting emotions running through him, with the strong need to make things right with Magnus, he still knew that the only way to save them both was to kiss Jace. How many times had he dreamed about kissing Jace? And now he was going to do it, in this nightmarish perversion of his forbidden fantasies.
Alec averted his eyes as he walked over to Jace, shame, anger, fear, sadness all running through him. His heart was beating so loud that when he finally stood before Jace, he would have worried that Jace could hear it. But he didn’t need to, because the bond had already synced Jace’s heartbeat with his own. Alec wanted to tell Jace – and Magnus – that this didn’t mean anything. But he couldn’t. Not when it meant everything.
Source: Trojan Horses – Chapter 1, by ArcticFox999 – Multifandom [Archive of Our Own]
A thrilling (and seriously hot) canon divergence from the Seelie kiss.