Firstly, please don't kill me! *puppy eyes*
Secondly, to be honest you took it better than I thought! XD
Always being compared to your brother can make you feel bad over yourself at first and then to make you dislike him a lot. My poor Aibaby... he will suffer. But if I want to be completely honest everyone will suffer! (I'm such a DoS ><) Sho will be in a torturous dilemma, Aiba... it's obvious and Jun! You pointed out correctly the reasons for this nasty behaviour of his BUT it's way more complicated than that! There are a lot of things hidden!
I would never make Jun a jerk because he really is! I chose him because I believe that he could pull out this character (he had to be sexy to lure Sho right?! ;) )

It means a lot to me that you will read this fic! I mean it!!!

Thanks a lot for your comment dear! <3