Writing scenes for him means getting into a specific kind of headspace. He's not a straightforward romantic lead, and trying to force him into that box falls flat. The attraction comes from power imbalance and twisted intimacy. A romantic scene with Doflamingo should feel like a negotiation where you have no leverage, but he's choosing to be charmed by your defiance anyway. Maybe you call his bluff on something, and instead of punishing you, he laughs, a real laugh that unsettles you more than his anger would. Physicality is key—he's a massive presence. The contrast between his large hands, rough from string control, gently tilting your chin up is more potent than any flowery confession. His words should carry double meanings; a compliment is also a threat, a promise is also a trap. The 'reader' character needs spine, though. They can't just swoon. The scene works when there's friction, when they push back just enough to make the eventual, inevitable yield feel earned and dangerously sweet.
I always think about control as the core dynamic. He has it all, so the only thing you can offer that has value is the choice to surrender it willingly. A romantic moment might be him offering you a choice between two terrible options, but you find a third path he didn't anticipate, and his admiration is genuine, if predatory. The setting matters too—opulent, gaudy, isolating. A private terrace overlooking the chaos of Dressrosa, his strings forming a delicate, cage-like canopy overhead. It's not safe, it's not healthy, but for that pairing, that's exactly the point. The compulsion comes from walking that razor's edge where affection and possession blur completely.