Why do you think Diavolos could be a good match for Raydan?
Raydan and DIavolos have so much in common. They were both born into and raised in situations that should have killed them, or, at the very least, turned them into bitter, hateful, rage fueled husks of human beings. But they’re not like that. They have honor and compassion and they care about people on a level that most others just don't. They’re born and natural leaders, each in their own way. They both know how to walk, talk, and act in places where they know they are surrounded by people who want them dead. They both know how to survive with everything they’ve got, no matter the cost, but as much as that’s true, if by sacrificing themselves they can save someone else, you bet your ass they’d do it.
Diavolos is so sick and tired and hurt by his life before Kenna that he’s the kind of person who never lets anyone get too close, he doesn’t trust anyone, not even his soldiers who he loves so dearly. He does what he can and what he should to be honorable and brave like any good prince should...but he can’t ever believe it will be enough to make people forget who he is, and who his family is. He’s seen his family torture and murder and laugh wildly about it and it sickens him, but he knows he’s got that part in him as well. And he’s trying to do his best to not be like them...but sometimes he’s worried that it’s something he’ll never be able to get rid of, something that will always be haunting his every thought.
Raydan grew up knowing that the world around him was a thousand percent awful, a thousand percent of the time, and you had to sweat and bleed to carve out even a split second of peace for yourself, Raydan learned quickly how to use his beautiful face and smooth husky voice to get what he needed without drawing a blade, though he could still do that if necessary, but despite being so charming and seemingly carefree, Raydan always knew what people did behind closed doors, what they said and did when no one was looking, and knowing how some people you look up to are actually awful at heart weighs on you. Raydan smiles and flirts but never lets anyone into the one safe place he has, his bed unless he can trust them. Needless to say, that’s a rare occurrence.
Once the two of them meet, they strike up a camaraderie, because, after all, they are the two people in the room that no one trusts, no matter what they do. Diavolos is a Nevrakis and they’re nothing but pure evil, and Raydan is the traitor who shot the Queen’s wife/best friend. So, as any two outcasts do, they start hanging around one another, and it sort of just...it’s just different, for both of them. Raydan flirts and charms and laughs, same as ever, and he can tell it’s working to some extent on the Prince, but it also...feels different. He can’t quite explain why there’s this strange sense of total understanding between them, even on opposite sides of the war table while planning battles. And Diavolos feels it too, but he tells himself to ignore the wide yawing pull in his gut that says, ‘This could be yours’. Because yes, Raydan is beautiful and he flirts and laughs at Diavolos’ sly complaints about courtly life, but nothing is ever truly going to belong to Diavolos, his father told him that long ago.
Their relationship deepens and strengths through this mutual feeling of companionship, built on the fact that they know the same things about life that would kill lesser men, and their conversations held quietly against the wall during a gala soon turn to equally quiet confessions about their lives and what has been done to them while staring at the stars. And before either of them knows it, they’ve confessed their deepest and darkest secrets to each other, because who could better understand than the other? And for Raydan, who’s spent his whole life shrouded in mysteries pulled tight around him like armor, that’s when it clicks. That’s when he looks at Diavolos, the cynical and love starved man with an honorable soul hidden beneath, and thinks, ‘Oh. Of course. It’s you. It’s going to be you.’ And Diavolos, who’s had to keep his cards tight to his chest since birth, hears that voice get louder, ‘This could be yours, look at him.’ But he can’t comprehend the thought that Raydan, who’s been beaten and bruised by life so many times and still has a heart of gold, would ever truly want him.
Then, during the battle against Azura, Diavolos nearly gets his head chopped off when he sees, from a great distance, Azura advancing on Raydan, lightning flaring from her fingertips and scorching through the air and even through the distance and the clamor of the battle, Diavolos seems to hear Raydan’s soft inhale of resignation just before it strikes. But then Val screams, shoving her way between them, and Diavolos has to turn back to his own part of the battle, the terror and rage of seeing Raydan in danger fueling him to push harder and farther, his soldiers following suit. And when they are later all within the throne room and his father lies dead at his feet and his blood stains his sword, he hears Raydan chuckle in relief. “Oh thank hea-” But Raydan doesn’t get to finish because Diavolos has strode over to him, shoved him against a wall and kissed him, fiercely, deeply. Kenna calls them to her as Azura still advances, and just before they turn back to the battle, Diavolos whispers to Raydan, “I was not going to let either of us live a moment longer without doing that.” Raydan grins, eyes bright and mouth red, “You’d better not die on me now, Prince, I have plans for you.”
Kenna wins, because of course she does, and the whole Five Kingdoms armies are celebrating and drinking together, and even Azura’s army celebrates with them, to a new era of peace across their great lands. But Diavolos and Raydan are not there. They are off in the distance, kissing lazily and laughing against each other's skin under the stars, drunk off of being alive and being together.
TLDR: Raydan and Diavolos can understand every facet of each other and would be the most supportive, loving couple ever.