Age 15
At the Konoha training grounds, far from the tumult of the village, Y/n and Shisui were face to face, circling each other and ready to lunge at every moment. They both had one of their sparring sessions which usually ended up with one of them giving up to not hurt the other and them both sharing some sweets from a small local shop they visited often.
Both were determined to win. Shisui grinned and activated his Sharingan. “Hey, that´s not fair. No Sharingan!” Y/n shouted at him. “Life´s not fair love. You have improved a lot since our last spar. But are you sure you can keep up with the legendary Uchiha Shisui?" She had blushed at the pet name. For some time Shisui had started calling her pet names and she didn´t know what to make out of it. Love, darling, princess… they did not help her crush on her best friend. She had to focus.
Y/n chuckled, her hair shifting slightly as she adopted a combat-ready stance. "Don't underestimate me, Shisui. I'm not going down without a fight." He only flashed her his beautiful, charming smile, and with a swift, fluid motion, Shisui lunged forward, his kunai flashing in the sunlight. Y/n dodged it, her kunai ready in hand. Their blades clashed, each strike resonating with precision and skill. There was no way she could outsmart him with his Sharingan activated. She had an idea but didn´t know how he would react and if it was going to be effective. As they engaged in different attacks and counters, Y/n let out a flirtatious remark, putting on a slightly suggestive tone to her voice. "Is that all you've got, Shisui? I was expecting a real challenge." He countered all her attacks and managed to get a firm grip on both her forearms holding them in between them, trapping her effectively.
Shisui chuckled, their faces mere inches apart as they sparred. His face inched closer until he was close to her ear. "Oh Y/n, I have so much more to show you, of course only if you think you can handle it.” She blushed furiously and blew some smoke into his face, creating a cloud of dust and lighting it up with a click of her teeth. The cloud erupted in flames. At least she could blame her flushed cheeks on the flames in front of her.
He was gone. She slowly turned around, scanning her surroundings. Where was he? He was called Shisui the Body Flicker for a reason. With her chakra, she slowly created a chakra net on the floor which was spreading further and further. With it, she could track all the movements in her surroundings. They knew each other's techniques and strategies so well that their sparring sessions were as much a test of skill as they were a chance to enjoy each other's company. She found him. While checking her surroundings she sensed his chakra. His chakra signature was engraved in her brain. She would find him anywhere. And he knew it, which is why he was suddenly standing behind her, holding the kunai to her neck. Damn it he was fast! She turned her head, looking up at him and showing him the greatest puppy eyes she could muster while wetting her lips and pouting innocently. His gaze faltered. Y/n took advantage of that momentary opening and swept Shisui off his feet, sending him to the ground with a gentle thud. She stood over him, a playful grin on her face. "Looks like I win this round."
Shisui laughed as he lay on the ground, his gaze fixed on the girl above him. The sun behind her gave the impression of a halo around her head while she was basking in the orange light of the afternoon. He was mesmerized, to say the least. Why did it have to be her? Why did he have to fall in love with his best friend? He couldn´t risk this friendship. The Uchiha´s were already frowned upon by most of the villagers, and he couldn´t lose her. So, he just enjoyed every intimate moment he had with her. Tried to memorize every little mark on her face, everything that made her smile, what she disliked, and tried to not think about pressing his lips against her every time he was on the receiving end of one of those dashing smiles.
She held out her hand to help him up. An olive branch is being handed out. But Shisui, mischievous as he is had other plans. He took her hand in his and made a calculated move, attempting to bring Y/n down to the ground. With a swift motion, he lunged toward her, aiming to pin her to the grass. However, Y/n knew him very well and with her quick reflexes and agility, interjected his plans.
As Shisui moved in to execute his manoeuvre, Y/n expertly countered his attack. She deftly moved her body, using his momentum against him. In a fluid and graceful motion, she flipped them both over, and suddenly, she was on top of Shisui, pinning him to the grass. She was straddling his thighs, pinning his arms to the ground. And he let her. She knew that if he wanted to, he could´ve won easily against her. Now their faces were mere inches apart. Shisui´s Sharingan was still activated but his gaze softened as he met Y/n's eyes. "Impressive move darling, but do not underestimate me.” Sending her a wink he grabbed Y/n and used her own momentum to roll them both down a grassy hillside. They had reached a part of the training grounds that had a slope. Shisui and Y/n tumbled down together, laughter escaping their lips as they lost control. Shisui held on tightly onto her, his arms encircling her waist while she wrapped hers around his neck.
When they finally came to a stop at the bottom of the hill, Y/n found herself on top of Shisui again, but this time their bodies closely intertwined. Their laughter faded, replaced by a silence filled with unspoken emotions. Their eyes met, and for a moment, time seemed to stand still. Shisui's Sharingan was like a swirling pool of mystery, drawing Y/n in. She was always fascinated by his eyes. Many feared the power of the red orbs, but she knew a different side. She knew of these red eyes trying everything to protect others. She knew of these eyes that had saved her countless times. And now she was so close to them. So close that their noses were touching. Y/n's eyes held a warmth and affection that was impossible to ignore.
A blush crept on Shisui´s cheeks mirroring Y/n`s own. The tension between the two friends was electrifying. They found themselves drawing closer and closer until their lips were only an inch apart. Shisui watched her carefully for any sign of discomfort. Seeing none he saw it as his cue to close the gap between them. “NIISAAAAAAAN! Where should we train?” Jumping away Y/n and both scrambled to their feet at the sound of a child´s voice. Faces red as a tomato they both watched how a little Sasuke came into view followed by Itachi. When Sasuke saw them both he immediately ran over. “Shisui-nii, Y/n-nee, look Nii-san will teach me how to throw shuriken today.” They both tried to sound enthusiastic while talking to Sasuke concealing their disappointment of their moment being gone. Shisui and Y/n knew what would´ve happened if the little Uchiha hadn´t disrupted them. They were going to kiss each other. And both wanted to do it.
Itachi the smart person that he is realised what was going on. Only raising an eyebrow while looking between Shisui and Y/n he chose not to say anything to not embarrass them further. Sasuke continued rambling and in the end Y/n and Shisui stayed to watch the lesson and occasionally voice their input. Neither mentioning what nearly happened.