Chapter Text
It’s sinful. Unbecoming of someone in his position. For him to want something so salacious, so lewd. Even if he knows how wrong it is, he can’t stop himself from indulging in the fantasy as he leans back in his seat. Falling deeper into the daydream, his imagination so vivid that he can practically feel your skin beneath his fingers.
Diavolo shouldn’t be thinking about you this way. No, he’s supposed to be above lusting after a human. So he shouldn’t be imagining your delicate human body straddling his lap, shouldn’t be thinking about how wonderfully tight your opening would feel as he sank into you. You’d take him so well, he just knows it, and he can imagine the way you’d whimper for him.
His hand drops to his lap, letting his fingers work to open his belt and pants. Wrapping his fingers around his member, he gives it a few lazy pumps. Thinking of the little gasp you might make when he pulls your hips down, burying his cock inside of you and holding your hips. You’d quiver on his lap, squeeze his hips with your plush thighs, bury your face in the crook of his neck to try to hide the way you’d blush.
He shouldn’t be doing this. Casually pleasuring himself as he fantasizes about bouncing you in his lap while he sits behind the desk. You’d fit so well against him, though. He groans quietly as he continues and bucks his hips, smirking when he imagines you crying out his name. Diavolo wants to hear his name echo off the walls of this room, ring through his castle, as he makes love to you.
The future ruler wants you to be his. He wants to have you in so many different ways, wants you so badly that it makes him ache. Dropping his gaze, he imagines you splayed across his desk with your thighs spread for him and your wrists bound above your head with his tie. His teeth sink into the inside of his cheek when he thinks about you writhing as he laps at your warmth and eases his fingers into you. He wants to taste you, touch you, but he knows he can’t do that.
No, he’s not supposed to crave you like this. Not supposed to want you. That knowledge can’t quell his desire, though. It’s been getting more intense. Growing steadily since the day he met you, when you arrived in the Devildom.
If he gives in to his desire, it will ruin everything. His plans for peace between the three realms could totally shatter if he gives in to his urges. Touching the cute human exchange student, possibly even taking your virginity and tainting you…it would look terrible. What sort of message would it send if word got out that he slept with you?
His hand slows and he squeezes himself gently, sighing. Diavolo tips his head back and opens his eyes, a frown tugging at his lips. This felt so good when he started, but the knowledge that his fantasies can never come true has ruined it. The warmth he’d felt, the pleasure, is replaced by a coldness…a loneliness.
The room is all his right now. Barbatos is occupied with making a snack and Diavolo knows he’s got a little more time before he returns. With one hand, he slips his cock back into his pants and closes the zipper. His other hand reaches for his phone and he opens his photos, scrolling until his golden gaze falls upon his favorite picture.
It’s the only picture he has with you. Taken the day you arrived in the Devildom. You have this adorable, sheepish smile on your face and you look so delicate next to him. He has his arm around your shoulders and the brothers are in the background, but that’s not what he focuses on now. Diavolo is more interested in that hint of warmth on your cheeks and the way you leaned into his touch.
He wants to get closer to you, even if he can’t have you completely. Just to have you sit in his lap or to wrap his arms around you. To have you smiling up at him and lacing your fragile human fingers with his powerful demon ones. Even just to talk to you, to have you in the room with him, would satisfy his desire for a while.
Diavolo can’t invite you to spend time alone with him, though. He could invite you, Solomon, Luke, and Simeon under the guise of wanting to meet with all of the exchange students, but that isn’t what he wants. While he does want to hear more about your life in the human world, learn about everything you enjoy there, he wants to have you all to himself. You and Solomon might have some things in common, you could bond over them, and that’s what Diavolo wants to avoid.
What he wants is to have you sit with him and tell him all about yourself. To be able to chat with you to his heart’s content. The rest of the world and all of his duties fading away into the background, leaving just the two of you. If he gives in, if he does ask for you to visit him on your own, it will look bad. Someone might think he’s playing favorites with the exchange students.
Sighing, he wonders if he can find some excuse to visit the House of Lamentation so he might at least catch a glimpse of you. He could go there under the guise of just speaking with Lucifer about how you’re adjusting. As soon as this idea sparks, he’s rising from his chair and crossing the room. The sooner he leaves, the sooner he can see you again and that thought is enough to bring a smile to his face.
Lucifer greets him formally when he arrives. Welcomes him into the house with open arms. “What brings you here tonight? Is there something that you needed to discuss with me? I could have saved you the trouble of coming here and gone to the castle-”
“No, no! I wanted to get out of there for a while, anyway. It’s good for me to get some fresh air every so often. Besides, I was hoping to see Y/N. Are they here?” Diavolo can’t stop himself from glancing around, hopeful that you might make an appearance. The thought of you popping up from around a corner makes his heart pound and he’s already grinning.
“I apologize.” Lucifer’s welcoming smile falls to a frown and he shakes his head, his eyebrows furrowing. “I think Y/N went to bed a little while ago. Do you need to talk to them? I can wake them up, if you…”
“Ah. No, that’s alright.” He feels kind of sheepish for visiting, for hoping. Of course you’re probably asleep; it’s kind of late for a visit, after all. It’s just a shame. Now all he can think about is how you must look right now. Snuggling into your pillow, wearing pajamas, you’re probably adorable. He’d love to have you fall asleep curled up in his lap.
“If you’re certain. I should make my rounds soon, regardless. I need to make sure that they don’t have any guests in their room tonight.” The other demon sighs and runs his fingers through his dark hair. “If I catch Mammon in their bed with them again…”
Lucifer has to be able to sense it. The fact that Mammon has, in fact, ventured into your room and made himself comfortable in your bed. The two of you are lying close together, both in your pajamas, with you showing him some videos on DevilTube. That was his excuse for being there; gruffly saying that he’d graciously offer you some company before you fall asleep.
You try not to act too nervous, but it’s difficult when he’s so close. It didn’t start out like this, of course! At first, he was at the edge of your bed and he gradually moved closer until his side was pressed against yours. Now his arm is wrapped around your shoulders and his face is so close to your own.
Warmth fills your cheeks when you catch the scent of his cologne. He’s acting nonchalant; laughing at the videos you show him and joking with you. Mammon seems completely unaware of how fast your heart is racing or how you can’t fully relax. There are butterflies in your stomach and the fluttery sensation gets stronger when he slips a leg between yours so you can be even closer.
It’s a fun way to unwind after classes. Really, it should be easy for you to relax when you’re doing something this fun, this comforting. Maybe it’s the warmth of his body against your side or the way he laughs. Maybe it’s the way his arm squeezes around your shoulders and he grins when one of his jokes makes you giggle. You’re happy, but you’re also anxious.
You’ve been in the Devildom for a while, now. Long enough to get close to all of your housemates, but you still find yourself almost always with Mammon. Even if you’re hanging out with one of the others, he’s usually not far away. Lately…you’ve found your gaze drifting to him more and more. There’s this expectation that you’ll just have to glance over and you’ll find him standing next to you.
You’re so wrapped up in your own nervousness that you, thankfully, don’t notice how flustered he gets. Oblivious to how his cheeks burn when he sees you smile or when you thank him for something. He always has to look away, always lifts a hand to hide his grin when he finds that he can’t contain his joy. Just spending time together like this, doing something as simple as watching videos together, makes him so happy.
Mammon thinks he’s doing a pretty amazing job of keeping up his aloof act. Telling you that he’s just there to keep you company while you fall asleep, giving the excuse of protecting you when he follows you around. Makes him sound pretty sweet, doesn’t it? What a nice, caring guy! The kind of guy you’ll wanna stay close to, right?
He just hopes you can’t see him blushing in his reflection on your phone screen. His cheeks are burning all the way to his ears. He can try to lie to himself, try to convince himself that he only did this so you’ll owe him a favor later, but it’s futile. Mammon knows that he’s here because he wants to be.
Having you cuddle up against him is a dream come true. You’ve got really thin pajamas and this is one of those few times that you’re not wearing a bra or a chest binder. You smell soapy and fresh since you just finished a bath when he came in. The best part of this, by far, is how close he’s able to get to you. Pressing his leg between both of yours, it’s so warm and soft that it makes him stiffen up.
Mammon doesn’t want this moment to end. He doesn’t want to go to his own room and have to sleep alone. Lucifer won’t allow it, though. No, he knows his brother well enough to know he’ll drag him out of the room by his ear. There’s no way Lucifer would ever knowingly let him sleep in your bed.
That knowledge doesn’t stop him from trying. As the minutes pass, Mammon glances at the time and when he hears footsteps in the hallway, he makes his move. “Don’t say anything to Lucifer, got it? I’m gonna hide in the closet so we can keep hangin’ out. You want that, right?” He’s already getting off the bed and raises an eyebrow, meeting your gaze.
“Ah. Yeah. That…that would be okay.” Heat is spreading across your face and you look down, trying to hide it from him.
You glance toward the door as Mammon hides, the footsteps getting closer. Slipping beneath the blanket on your bed, you lean against your pillow again and scroll through DevilTube to find another video to watch once Lucifer leaves. Something cute? Maybe something funny would be better.
The door clicks open and the eldest brother stands in the doorway, his black and red eyes focusing on you. For a moment, he seems perplexed, but then his expression softens slightly. “Y/N. Do you know how late it is? I thought you would be asleep by now.”
“Um. I’m kind of having trouble falling asleep so I was watching some videos.” You can feel sweat beading on your skin and try so hard to not glance toward the closet. Hoping Mammon won’t make a sound to give away his hiding spot.
“I see.” Lucifer approaches the side of your bed and looks down at your phone. Tilting his head slightly when he sees that you’re looking at videos of catlike monsters playing in boxes. “Lord Diavolo is waiting for me. I believe he wants to discuss how you’re adjusting to life here. Once he leaves, I can come back and help you fall asleep, if you’d like.”
“Ah! N-no, that’s okay! I don’t want to be a bother and I know you’re probably really busy, Lucifer. I’ll just watch a few more and try to go to sleep,” you assure him. Your lips curve into a smile, trying to convince him. Though a part of you is curious how exactly he’d help you fall asleep. Some sort of magic?
“It’s not a bother.” A gloved hand rests on the top of your head and ruffles your hair. “I’m sure I can help you relax better than Mammon can.” His eyes dart in the direction of the closet, a cold smile on his face.
It’s a shame. Mammon really did try to be quiet, but he still got caught and tossed out of your bedroom. He’s stuck standing out in the hallway while you undoubtedly get a lecture from Lucifer behind that closed door. Frustrating as it is, there isn’t much he can do at this point. If he hangs around, he’ll be lectured next so he decides to just go to his room.
Maybe when it’s really late, when he’s sure Lucifer is asleep, he’ll sneak back into your room. He grins at the thought of slipping into your bed and sleeping next to you. It’s only fair that he gets first dibs on sleeping in your bed, right? After all, you were entrusted to him! Sharing a bed is technically him looking after you!
His steps slow as he notices a figure further down the hallway. Cocking his head to the side, he wonders why Diavolo is there. Usually he’d stay near the entrance or go to the library if he was meeting with Lucifer. Mammon can’t remember ever seeing him in one of the bedroom halls before.
“Lucifer is in Y/N’s room, giving them a lecture,” he offers as soon as he’s within earshot of the future king.
“Ah. I saw you stumble out of their room a few seconds ago.” Diavolo chuckles, his arms crossed.
“Oh. Uh, well, I was just keepin’ them company until they dozed off. Humans get lonely if ya leave them by themselves and then they get clingy, you know?” Mammon looks away, focusing his blue and gold eyes on the wall. He can feel the blood rushing to his face when he talks about you and he doesn’t want anyone to see him getting so flustered over a human.
“You’re close with them, aren’t you? Would you say that you’re their closest friend?”
His eyes snap back to the other demon. “Of course! I’m their best friend! No, we’re even closer than that! We’re better than best friends!”
Diavolo beams and claps a hand onto Mammon’s shoulder. “So you must have plenty of pictures of them.”
“Huh? Well, yeah!” Poor Mammon has no idea where this is going. He’s just defending his position as your man. He’s your first so of course he’d be closer to you than his brothers would be!
“Would you mind showing me?” Still smiling, he takes a step closer to the pale-haired demon and leans down when Mammon opens the photos on his phone. Staring down at the phone screen, hoping to find some cute candid pictures of you…only to be disappointed.
Mammon does have pictures of you. Rows and rows of them. The problem is that these are all selfies that he’s taken with you. Images of Mammon with his arm draped across your shoulders, photos of you both on a walk at night, a handful of pictures of what looks like the two of you lying on your bed. You look so flustered in those photos and it makes the prince’s pulse quicken.
“Pretty good collection, right? This one’s my favorite.” He shows Diavolo a picture of you asleep, with your head resting against his shoulder. It really is Mammon’s favorite, but he can immediately see that it’s not what the demon prince had in mind.
“You don’t have any pictures of just Y/N?”
“Uh, no. Why? These aren’t good enough?” Feeling a bit defensive, he’s starting to regret proudly showing off his collection. It doesn’t matter anyway, right? All the more for Mammon!
Diavolo doesn’t answer at first. There’s this thoughtful expression on his face as he carefully considers his offer. When he does speak again, it’s with a gentle tone. “These aren’t quite what I was looking for. I need pictures of Y/N by themselves. Since you’re so close with them, maybe I could count on you to take some good pictures.”
“Huh? What? Really? You want me to take pictures of them and send them to ya? What kind do you want? Just some pictures of them studyin’ and stuff?”
“Any photos you can get, as long as they’re good quality and candid. I don’t want Y/N to pose for any of them; I want them to naturally capture their essence. So it would be best if you don’t tell them that you’re taking their picture.” Here it is. Something to feed his hunger for you, something for Diavolo to cherish and admire since he can’t get you alone.
“Oh! It’s for a collage or somethin’, right? For the exchange program? I can get some good ones of them tomorrow in class that you could use.” Mammon still doesn’t fully understand why the future ruler is making this request. He continues to scroll through his photos, wondering why the classroom pictures weren’t good enough.
Diavolo’s smile grows as he shakes his head. “They can be pictures taken anywhere. I don’t need them for a collage; they’re for personal use.”
That…makes Mammon freeze. His eyes lift to look at the other demon, waiting for him to say he’s joking. When Diavolo doesn’t admit that it was a joke, there’s this odd feeling in his chest. Flickers of jealousy clash against confusion and a certain sense of unease when he stares at Diavolo’s smile. “Huh? You said they’re for personal use? What, like you want ‘em to put on your desk?” Nervous laughter escapes him and he hopes Diavolo will laugh with him, but he doesn’t.
“No, you can just send them to my phone.” No one will believe Mammon if he tells anyone about this. Who would believe that Diavolo would request pictures of you for him to admire when you’re apart? Besides, out of all of the brothers, Mammon is the least trustworthy. His secret is safe, but it won’t hurt to make sure the white-haired demon has a little incentive to give him plenty of good pictures.
“Of course, I’ll pay you per picture and the price will be higher for the better quality ones. How about…?” He names a base price and sees Mammon’s eyes widen. “Well?”
It’s a struggle. Honestly, it’s in Mammon’s nature to want that money. He’s the Avatar of Greed, after all! It’s just that there’s this part of him that’s reluctant to do this. Something feels especially scummy about snapping pictures of you without you knowing and selling them to the Devildom’s future king.
A while ago, he might’ve done it without a second thought. It’s easy money and Diavolo is willing to pay him a lot per picture. Think of how much he could do with that kind of cash! But that was before he got to really know you, before he got closer to you. Now, he doesn’t even like his brothers seeing the selfies he takes with you.
What makes Mammon finally agree is the realization that this job will mean that he gets to spend even more time with you. If he’s going to get some good shots, he’ll need to stay nice and close. Maybe Diavolo will even convince Lucifer to ease up on him and let him sleep in your room. So, grinning, he accepts the job.
“If ya want me to send you some tonight, I’m gonna need to get into their room again. Lucifer’s in there lecturing them now, but if you can distract him when he comes out-”
“I’m sure I can keep him preoccupied for a while,” Diavolo assures him, chuckling. He rests a hand on Mammon’s shoulder again and beams as he leans down a bit. “Just one more thing. Make sure you don’t stay in their room overnight.” His fingertips press harder at the other demon’s shoulder in a silent warning and he sees Mammon rapidly nod in understanding.