Benny was a prison inmate working secretely for Bejo.
He is first time seen in the toilets, with all the mob sent to beat Rama. He is beaten by Rama, who is now under the name of Yuda, accused of beating the son of an important politician.
Then, at the canteen, he is presented by Uco as one of his most trusted men inside the prison.
After this, a violent riot occurs in the prison patio, when Benny and many other men try to kill Uco, Benny himself fights Uco and even wounds him, before being stopped and beated by Rama.
After his betray, he is captured by Bejo's men when he gets out of the prison and is given as a gift for Uco, for revenging himself. Uco looks at Benny's tattoo just before cutting his throat.
By the end, Uco realizes that Benny had the same tattoo as Bejo, so he was one of his men, by discovering this, he realizes that he was cheated by them.