It appears, fellow Summoners, that we had been misguided in our wild hypothesis with regards to Nasus' brother, Renekton. We all assumed that he was some sort of power hungry member of Nasus' race, or a traitor to his own kind.
We were wrong.
Indeed, Renekton was originally a noble fellow being as Nasus is, being the gatekeeper to this 'Great Library' of their homeworld, sensing and turning away people with dark ambitions. However, continuous exposure to these dark thoughts and ambitions had rendered him insane.
Our condolences to the noble Curator of the Sands, for your brother is not fully at fault for his actions. The dark side of nature is corruptive, yet maddening.
On another note, I suggest researching a way to perhaps reform Renekton, for he did not deserve this for simply doing his duty as the gatekeeper.
-Summoner Raziel, the Phantom of Chaos