Brother of Predation

An avid reader of Tensura is reincarnated into the story as Rimuru's brother. With all of his memories intact. With an abnormally strong soul and a plethora of skills, he decides to have some fun. Give Rimuru a few more unique skills, manipulate the villains a bit, and change the course of the story into something he finds interesting while having fun.

But the story won't stay the same with his intervention, and the other characters will take this new variable into account.

But more importantly, how will Rimuru react to this extremely suspicious "younger brother" of his?