Kylo was hurting, that much was obvious. He brought up how he knew about Isleen and him but that wasn't what upset him the most.
Dew... So that was the name of the dead fairy girl? And she was Kylo's mate? It all made sense now... The vampire killed Dew to get to Kylo. She was a distraction.
But how could he explain that to his son when he looked so bent on killing him?
At the end of Kylo's lamentation on all the ways Rhett had failed him as a father, the latter felt regret. He should've been there more for Kylo's growth, maybe then he wouldn't have been easily manipulated.
When he noticed how emotional Kylo was getting, he took the opportunity. "And I hope you can forgive me for what I'm about to do..."
Not waiting for Kylo—who was now standing just inches away from his table—to make a move, Rhett sent a mental signal to Aceco through the magic link she'd created between him and her.