Mei and Rei were in Rei's dimension. In the middle was a big wooden house made from mokuton.
These days, they started feeling quite cramped in the two-bedroom flat so Rei decided that they would use it only as a 'cover' and instead live inside his dimension. It was not like anyone could get through the security seals in his apartment and if anybody came, he had prepared an alert seal.
They couldn't keep this from Mei as she lived with them so the secret was out and Mei was taken to Rei's dimension and even witnessed the Mokuton of Rei and Konan as they raised the house. For now, Mei had a secrecy seal on the upper part of her mouth.
She was all huffy about them keeping this from her and actually had her first childish fit. Rei even had to promise her to take her as his wife to make her stop being angry!
Outtalked by a kid... Rei depressedly thought.
Well, at least he managed to argue that she would first have to be fourteen! Rei was feeling quite betrayed too! Both Tsunade and Konan joined little Mei and verbally ganged up on him! He was literally pushed into a corner and couldn't run!
"Yes, like that!" He exclaimed as he watched Mei produce a small fire through fire chakra alone. The feat was very hard and very draining but it would help her immensely later on in katon Jutsu.
She finally managed it after a week of continuous practice. Rei hugged her tightly and Mei melted into his hug.
Patting her head with a slight smile, Rei spoke.
"Now... I think it is high time to teach you about your Futton."
Mei froze in his embrace. Futton. She remembered vividly how she melted her best friend. The screams, the blood, the melting flesh. She tightly closed her eyes to keep the images away.
Rei seeing it, squatted in front of her, and pressed his lips on her forehead, sending a calming pulse of suiton chakra through her brain. He pulled away and smiled at her.
"It's fine Mei." He ruffled her hair. "Futton is your strongest but most brutal offensive. It will take time for you to get used to it. Will you try, please? For me?"
Mei was conflicted. She was scared and didn't want to use that thing again. But... Rei asked it out of her. She timidly nodded, still trembling.
Rei knew she had trauma and her biggest fear was her futton bloodline but he had to get her out of it. He spent months on getting her to regard him as someone trusted. Someone, she felt safe with. It was time to push and make her accept her powers.
He took the upper part of her hand to his palm and gently turned it upwards, her palm facing the sky as he raised it closer to her mouth.
"You know what to do." He whispered to her.
Mei was scared witless. He wanted her to try it while he held her!? She shook her head in fright, her eyes tightly closed in refusal as she was afraid she would hurt him but his suiton chakra calmed her.
She opened her eyes and her heart froze. She was... bathed in flames. Bright blue flames danced all around the clearing, Rei, herself... but other than a pleasant chill, she felt nothing. The flames also harmlessly flickered, as if lazily all around the clearing.
Rei smiled at her awestruck expression as she looked around. This was the first time he showed her his katon/suiton/nature mix and he felt proud he made the kid all sparky.
"This is my mix of suiton and katon." He told her slowly and Mei's eyes widened even more as she intently listened to Rei. "It is not Kekkei Genkai like yours." He told her, making her slowly nod. "But it is similar. As you see, I can completely control it," He pointed at a tree behind her and Mei turned around only to see a tree slowly freeze, becoming completely white until it shattered into smaller parts. These smaller parts then became smaller and smaller, until only snowy dust remained of the massive tree.
"You can also gain such control. All it needs is a practice." He told the still gaping Mei as she realized just how dangerous these flames were. "So... will you practice with me?" He coaxed her and Mei nodded, somewhat excited.
Rei ruffled her hair again. "Good girl." He smiled at her, making her blush, and their practice of Futton started.
...
Three weeks passed and Mei was 'sparring' with Rei. Her advancement with her futton was almost as fast as Konan's with her paper and by now, Mei could create a somewhat thin mist of acidic mist. She was far away from real boiling mist but it was a start.
Rei didn't make her actually master her katon, suiton, and doton. He only taught her the basics and some of his own exercises that were incredibly hard but would teach her how to properly manipulate her elemental chakra. She would instinctively pick up on her natures as she used her Kekkei Genkai so it was pointless to teach her more.
But... his tutelage already showed as she spewed mist at him when he came closer. He let her hit as always, to make her stop being afraid of melting him. Rei observed that Mei had utter disregard for anything that was not Rei, Konan, and slowly but steadily Tsunade was getting on that list.
When he first brought an animal... she melted it with her acidic mist and didn't even twitch. But when she was to use it on Rei? She was all shaky and stuff. He couldn't have that.
"More output, Mei." He admonished her as his hand grabbed her by the neck and lifted her from the ground. Her legs dangled as she choked. It was quite a familiar sight these days as constricting her neck and preventing her from spitting more mist is the FIRST thing an enemy would do. Rei didn't coddle her and did it too with brutal precision. It showed her swiftly how weak and powerless she was when her neck was held. And while Mei had more often than not had to go to Tsunade to treat a palm-sized bruise on her neck... she slowly learned to not panic and more importantly, to NOT lose control and burn her neck from inside.
Rei had to save her quite a few times when he did it the first time. Fortunately, he had the foresight and pumped a lot of suiton and katon chakra through her neck, offsetting her own bloodline as he grabbed her neck and she lost control. Otherwise, she would melt straight through it from inside. Her Kekkei Genkai was a dangerous thing. While she had unconscious control and protection, once she panicked...
Rei's tactic was simple. He did it so many times, always in a different way, always startling her, making her lose control. As they practiced, he started putting in less and less of his own chakra to offset her own when she lost control and Mei was starting to consciously do what he did with her own chakra. It worked for the last three days, not even once did she burn the inside of her own neck even though he didn't safeguard her anymore.
As his hand held her neck, he had to let her go as her right hand slashed at his wrist with a kunai.
"Good." Rei praised her and his hand quickly struck the kunai, making her drop it while his second hand again violently grabbed her neck while her body was still mid-air.
Mei hated this exercise with passion but she knew exactly what Rei wanted from her. He wanted her to let out her maximum output of futton right into his face as he held her neck. She knew she could do it days ago when she mastered protecting her insides from the mist. Deep down, she was still afraid of hurting Rei though.
Closing her eyes as she choked, she decided to believe in Rei and let out her futton.
Rei suddenly found himself covered in a white translucent mist that irritated his skin slightly before he raised the output of suiton chakra in it, negating the mist.
He let Mei go, making her fall to the ground and start coughing as she gulped the air greedily.
He squatted near her and ruffled her hair.
"That's my girl. Keep it up. Don't be afraid of your own power. Master it."
Mei raised her head, her eyes exhausted from all the choking she was put through today. But she was happy. Her mind was... free. She bathed Rei in her mist and he didn't melt! Her childish mind completely lost all fear for her futton and Rei couldn't help but praise himself.
A brutal method it may be but the girl learned to guard one of her most vital weaknesses and stopped being such a wimp about her bloodline. A win-win in my books... He grinned at her.
"So... up for ramen?"
Mei instantly jumped up and embraced his waist, making him laugh.
"Sure you are. You glutton." He took her into his arms and left towards the house.