First things first, this was not Yukio's fault. Well, not exactly. Rin and Yukio had been studying when Rin suddenly cried out and fell of his chair "son of a b-!" Yukio rushed over "Rin, what happened?" Rin growled "I banged my tail on the edge of the table".
That was the first time Yukio realised that Rin's tail was the most sensitive part of his body and for a while, he respected it and tried to stay away from touching it. That was, until Rin thought it would be funny to prank Yukio during lunch. Though a flaming hot bowl of soup went down his throat, Yukio kept his cool and simply glared at Rin who was on the ground laughing. Yukio didn't get mad often, instead, he gets even. The next day, Yukio passed Shemi in the hall and he had an idea "Shemi! Could I talk to you for a moment?"
In class, Rin passed a very quiet Shemi and a sheepish looking Suguro. The lesson went on as usual. Then, Rin felt something brush his tail. He flinched and let out a squeak "something wrong, Rin?" Yukio asked. Rin narrowed his eyes "nothing you need to worry about" he snorted. Yukio raised an eyebrow but continued the lesson. When class ended, Rin had to bite his toung as Izumo stepped on his tail 'accidentally', Suguro dropped his bag and Shemi closed the door on his tail.
Having a pretty good guess about what had happen, Rin stayed behind "Yukio, what the Hell was that?" He demanded. His twin looked at him surprised "what on Asshai are you talking about?" He said curiously. Rin's lip twitched and he growled "you know what! Telling everyone to pull and step on my tail!" Yukio smiled "and why would I do that?" He taunted. Rin's muscles tensed "to get back at me! Why else?!"
Suddenly Yukio was behind Rin "so sensitive that if I was to do this" he brushed his hand over the fluffy part of Rin's tail. Rin locked up and sprang away, hissing "what's your problem Yukio?!" He said "your cute when your mad" Yukio replied. Rin stopped and tilted his head "what did you just say?" But Yukio didn't answer "come on Rin, it's getting late" and with that he left Rin, blushing and confused.