For a while now I've been thinking about how there isn't that much out there for IbxMary, so this is my contribution to the fandom.
Disclaimer: I don't own Ib or any of the characters
"Quiet, someone might hear us."
Ib fought the temptation to roll her eyes. Between the two, Mary had been making enough noise for the both of them. Seeing her expression, Mary giggled and returned to the task she had been working on.
She leaned forward and gently placed another kiss on Ib's cheek, all the while tenderly running her fingers along the other girl's sides. Each movement was tantalizingly slow and methodical, designed specifically to get a reaction out of her.
Despite her best efforts, Ib couldn't help but let out a shiver of pleasure at her caress. Mary took this as a silent signal to go further. She positioned herself above the brunette, so that Ib's head rested gently on her pillows, and began placing tender kisses on her exposed neck. Ib was helpless to do anything other than nuzzle Mary's shoulder and moan softly.
This was the game they played. Each one would try to work their magic on the other, all the while doing their best to avoid losing themselves to their partner's touch. Sometimes it was a gentle affair. Both of them would lay next to each other, whispering sweet words as their thoughts turned to not-so-sweet actions. Other times they would be far more aggressive, pushing their limits like hungry animals.
Regardless of how they went about it, the goal was always the same. Work the other up until she could hardly stand it, before making her admit who the victor was.
In all the time they had been doing this Ib had never lost once.
She had a secret weapon that Mary simply couldn't combat against. A single phrase that never let her down no matter how many times she used it. Sometimes Ib would wonder how so few words held such power over the blonde girl, but in the end it didn't matter. She was happy to say them as many times as Mary needed to hear it.
An electric shock of sensation shot up Ib's spine as Mary slipped her fingers under her shirt, running them along the exposed skin underneath.
"Ready to give up?" Mary said, grinning at Ib's gasp.
The red eyed girl took several breaths to ensure her voice wouldn't falter before responding. "Not today." She said with an answering smile. "I'm still going to win."
This was exactly the answer Mary had wanted to hear.
"I don't think so." She said leaning even closer. "Today's the day I beat you." For a moment, Ib's entire world consisted of two bright blue eyes. Two tranquil oceans that swallowed all other things in their beautiful stillness.
Then Mary's mouth was on hers.
The soft touch of her lips set off an explosion in Ib's mind, wiping away conscious thought. Her body responded on its own, pushing up off the mattress in an attempt to get closer to the other girl. Her arms wrapped around Mary's body, on clinging to her back while the other rested softly on her head.
Without warning, Mary broke off the contact leaving Ib whimpering slightly at the sudden disappearance. Opening her eyes to see what the problem was, Ib was greeted with a mischievous smile. It was then that she realized the tactics Mary was employing.
The blonde leaned forward once more and continued the kiss. This time however, she didn't stop there. As she kept her lips on Ib's, her hands worked along the other girl's back and up to the clasp on her bra.
Ib let out a muffled yelp as she felt the touch and pulled back quickly. Mary just laughed softly at her reaction.
"What's the matter Ib?" She asked teasingly. "Can't keep a hold of yourself?"
Ib's face had turned to an almost pure crimson as she reached back to make sure the clasp was still intact. Her size was a rather sensitive subject, something that Mary was using to her advantage. Despite how quickly her adopted sister had grown into her teenage body, Ib had remained fairly unremarkable. While Mary got unmistakable glances from half the boys they knew, she remained almost unseen.
It's not that she particularly wanted boys chasing after her, but some attention would be nice.
Ib decided that now was the time to start pushing her own advantage. After all, two could play at that game.
Pushing up off the bed, she forced Mary back until their positions had been reversed. Now Mary lay with her head at the foot of the bed with Ib on top.
"You know…" Ib said, whispering into her ear. "I think it's time you remembered who's in control here."
She felt hot breath on her neck as Mary's pulse picked up. Both of them knew where this was going.
"In case you've forgotten, I have four magic words that will make you do whatever I want."
The girl beneath her let out an unconvincing chuckle as she tried to save face. "No you don't" She said. "T-That won't w-work so easily this time!"
Ib raised an eyebrow with a predatory smile. "Won't it?" She asked, tracing a finger up her collarbone. "How do you figure that?"
Mary fidgeted underneath her, but there was no way that the brunette was going to let her get away.
"B-Because I've been preparing for it. I made sure that I would be ready this time."
"Have you?" Ib questioned, leaning forward so that her mouth was directly next to Mary's ear. "How have you been preparing?"
The blue eyed girl's heartbeat was almost audible as it slammed against her ribcage.
"I've been…" She couldn't say anything else. They both knew no matter what she might try, those words would still hold absolute dominion over her.
Ib decided that the game had gone on for long enough. She drew Mary up to her and closed the distance for her own kiss. Unlike the earlier, teasing, contacts, this one was deep and passionate. Ib willed every ounce of feeling in her body to pass over to her partner, and convince her of the absolute truth behind her words.
After a miniature eternity, Mary fell back on the mattress. Her entire body had gone limp as she shivered in the intense afterglow of their touch. Her eyes were half-lidded as she fell entirely under Ib's control.
"Please…" She whispered.
"What was that?" Ib asked. She wasn't about to let Mary off that easily.
"Please… please say it." She pleaded. "I… you win, just please say it."
Ib felt a soft smile form on her lips at those words. She gave the begging girl one last kiss before she finally consented. Holding her eyes with her own, Ib spoke the four words that gave her such total control.
"I love you, Mary."