I can't even think if I, as the reader, missed any clues. My first gut reaction is the suitor/stalker element that WENT OVERLOOKED in Elisha's POV during their Second life, now that we know he exists and must have been thwarted somehow then.
My second gut feeling says it's Miguel, because of the entire lead up to bidding Elisha goodbye, and refusing to go into the parlor. But if it's Miguel, and likely something his father made him do, why don't we know more politically about the world or their relationship to each other (Vincent and Miguel.)
OR there's Yana's country that could be an element but why would they need to kill a random noble UNLESS THE GOAL WAS MIGUEL!?!?
Because despite his rank and his qualifications as a fiance, and the right he won to marrying Yana, it was the arguably most rejected event in the story thus far. Miguel wins Yana, Azraq leaves and there's not another political element added outside of Azraq receiving a mystery message.
My mind is racing after binging this one, and I adore it so much, so I thought I'd share lol