I don’t think he was taking any type of stimulant or other drugs. I think years of built up rage in him exploded that night of the murders. He’d been rejected all his life by young, beautiful girls like Kaylee, Maddie and Xana. They always had young handsome popular boyfriends, like Ethan.
He’d failed as a TA and was getting fired from that position, and was to lose out on obtaining his PhD. Another failure.
Although BK is very mentally ill, in my opinion he is evil. I am a person that firmly believes evil exists incarnate. Maddie, Kaylee, Xana and Ethan encountered it that night when BK slithered into their home.
Nope, I don’t believe any drugs coursed through BK’s veins that night, but evil rage sure did.
jmo