Kouen has changed over the years.
Judal sees it all very clearly, no matter how he himself jokes about his less-than-perfect memory. He remembers well being a small child of maybe five or six, being introduced to the royalty of the Kou Empire, and Kouen, their first prince, had thought he was cute enough to humor him. At least, that's how Judal likes to remember it, with Kouen proudly showing off his prized warhorse, an enormous chestnut mare that Judal remembers being tossed up onto at his own request.
Kouen had been fun.
The First Prince has always, always been strict, a little boring with how set in his routines he is, but there were times that Judal can remember him loosening up—just a bit. There were times when he tolerated Judal's desire to tag along at his heels, complaining about long, ceremonial robes the whole time, and so Kouen had sighed with the long-suffering of all of his 18 years, and scooped the Magi up to set him on his shoulders instead.
(There were also times that Judal doesn't like to recall, such as when he had first met Sinbad when he himself was only 14, had a long night that left him sweaty and sticky and exhausted, and subsequently found himself in a great deal of trouble for escaping hiskeepers. He hadn't liked the organization's idea of a punishment, then—
You desire a worthy king's touch, do you?
—and neither had Kouen, his nose turned up in distaste at the idea of bedding Judal, which had hurt his feelings a bit more than he wanted to admit, and it wasn't good, which made it all the more frustrating and worse.)
Over time, though, Kouen grows less tolerant, more annoyed, far more interested in his maps and armies, and that's fine, in a way. Judal likes the idea of war, likes the idea of crushing those that irritate him and spurn him, and he likes even more making Kouen happy. It's easy to make him happy by raising a dungeon or a dozen, and he does so specially for him and his siblings, for Hakuei, too, whom Kouen's eyes drift to more and more as of late.
Judal isn't jealous of that—can't quite find the ability to be, not when he's sighing just as stupidly out a window and imagining an island half an ocean away.
Still—he wishes Kouen would stay fun, would grin at him when he catches a peach meant to slam into the side of his head, would eat dinner with him again like no one else ever would, and would sit up late at night with him again, talking of all the things they'll do when Judal truly and completely chooses him, all the countries that will be underneath their thumb, all the power that they'll have.
And still—he wishes Kouen would touch his cheek once in awhile like he does Hakuei's, wishes the man looked at him and bid him to his bed on his own accord rather than Judal's whining, wishes even more that that same stupid mare was still alive, so Kouen could throw him up into her saddle and the two of them could charge into war together (no matter how Judal hates campaigns, likes far more the fighting and the fun of that instead).
Pipe dreams, all of it, and so Judal finds himself staring off at islands instead. Gods help him if Koumei tells him not to go again; he might just stay.