Complex sentence: Jason realizes how badly he's been beaten, so he confronts the leader of the gang, Alonzo (Treach), who is Lyric's brother, and the two have a vicious fight in a public restroom.
Split into simpler sentences: Jason realizes how badly he's been beaten, so he confronts the leader of the gang, Alonzo (Treach), who is Lyric's brother. As a result of this, the two have a vicious fight in a public restroom.