Let the demon have her fun.

You eye her sexy body and think of no other way you could answer, "Well, all right."

She grins and kisses you. You're surprised to find that her tongue as much longer and serpentine as she gently french kisses you, "Relax. You're going to experience pleasure most men only dream of." She presses herself against you and kisses you more vigorously. Her hands pulling your shirt off as she presses her breasts against your exposed chest. You squirm under her and put your hands on her hips. She licks along your neck and pulls your trousers down. Your stiff cock protruding from your underwear.

She grins at you, "Oh My, Your Majesty. What a nice cock you have." She rubs you through your underwear before sliding your cock out. She grins and stares at you excitedly with her violet eyes as she lifts herself onto your cock and slowly impales herself onto it. You gasp at the feeling of her warm, wet vagina wrapped around your cock and she starts to gyrate her hips. She moans and sits up to give you a good view of her bouncing breasts as she slowly rides you.

You tighten your grip on her hips and pull her closer to you, your cock piercing her deeply as she quickly speeds up on top of you. You lick her stiff nipple and thrust your hips up into her, not wanting her to do all of the work as you try and hit her sensitive bits. Her tail wiggles a bit and she pulls you against her breasts, almost smothering you in her lovely pillows as she starts to slide up and down on your cock quickly, moaning loudly for all nearby to hear. You squirm in pleasure as her muscles expertly contract and relax to maximize your pleasure. The sexy demoness clearly knowing how to work a cock with her body.

You feel a gradual build up in your loins as you quickly approach your limit. Suddenly she moans loudly in ecstasy and presses herself down hard onto you. Her wings and tail stretch to their greatest distance as her vagina twitches and spasms along your length as she comes around your cock. You release your own groan of pleasure as you get sent over the edge. Your body stiffens as your cock starts twitching inside the writhing succubus. A moment later your warm seed bursts from your cock and you release your essence into her.

You fall back in the chair feeling more drained than you should as she presses herself against you, looking pleased. "That was quite good. Most men don't even make me come."

You're still exhausted, but manage to pant out a "Thanks."

She sits up in your lap, causing an excited twitch from your cock and she grins at you. "So, I have an idea. I can change my form as well as possess people. The only reason i possessed the girl instead of taking her form was so that I could slip in undetected by any antimagic wards. What would you say if I took the form of Countess Marissa and then we get married?"

You sit up, finally recovering and ask, "what would that accomplish?"

She shrugs, "Well, The entire reason I'm here is because I'm bored. Perhaps as Queen, I could have a bit more fun in my life?"

You look down at where you're connected to the succubus to see your semen dribbling out of her from around your cock, "I have to think about my kingdom first. Right now I'm the only member of my family and if I die heir less, the kingdom will fall into disarray."

She runs her hand along your chest, "I'm perfectly capable of bearing offspring if I so choose."

You squirm under her, "Did you? I mean are you now?"

She giggles, "Of course not. I wouldn't risk bearing your spawn before you agreed to my suggestion. What would happen if you were to refuse? I would be stuck pregnant with your bastard child." she nuzzles her head against you, "So, what do you say? Not many rulers can attest to having a demon of lust and sex as their wife."

You consider your options. Demons are notorious liars. It's possible that she's lying about her current lack of fertility, or lying about just being bored and wanting entertainment. It's impossible to know what she might have planned, if she gets in a position of power. On the other hand, it's true that you will have to get married and produce heirs eventually. The longer you wait to do so, the more likely it is that something terrible might befall you and bring the realm to ruin. If she does become pregnant from this copulation, then it may be best to keep her close. So she, or her child can't cause trouble in the future.