"Has it not?" Kas did not need to psychoanalyze the situation; Kaidan had practically done it himself. It had always been about that child. "That wound, no matter how hard, you cannot seal. I’ve watched you try." If Sebastian were ever forgotten, the pain would subside, devaluing the work that had been done. "I was there. Searched endlessly for that child, and I failed you in that." Kas hadn’t needed to search at all. He knew exactly where Sebastian had been taken, having been the one to hand the child over in the dead of night. That night had likely been of the best-kept secrets in the fae realm—a scheme by Velar's King, one no soul in the realm knew of except Kaspar. It had been his task to keep that child lost.
What else his King once desired was lost—TRIAD had Kaspar now, with some promises to place him on the fae's throne, to return to his own rightful place - as the King's own heir. In exchange? Kaspar would give secrets guarded by the fae and guide them on how to twist a metaphorical dagger into Kaidan. It was by Kas that Triad dug into memories, learning how to use that something taken as a weapon, reopening old wounds.
From the very beginning, it had been Kas’ job to make them fester. In the Night Court, he was the eater, the conduit for the so-called nightmares of nightmares
"Wise men don’t breach a fortress without first understanding its inner workings." He tapped his temple lightly. "Do not let your mind be consumed by anguish. You must think clearly. You couldn’t allow them to take something you love, but they already have—before you even realized. They knew before you did. Someone led them to your heart. This means someone in your trusted circle is a traitor—and the task now is to find them and seize them." Kaspar would not point to himself, of course, but it was a delicate way of showing how easy it was for an enemy to hide in plain sight, and to make Kaidan question every choice.