From Halopedia, the Halo wiki
When Dadab arrived, Bapap was one of the few Unggoy who listened to what he said, and became strongly religious as a result. He was part of Dadab's ministry group and was one of its most enthusiastic members.
Bapap and Dadab soon became good friends. Bapap aided Dadab in his exploration of the orbital station Tiara over Harvest along with the Huragok Lighter Than Some. He fought alongside Dadab in an attempt to repel the humans, costing him his life when they shredded through the Unggoy’s body with several bullets.  Even at the very end of his life, he believed strongly in the Great Journey, discussed his fate with Dadab and place on the Journey. To prevent his injury from slowing the others down, Bapap was killed by Tartarus with a Type-25 Spiker. His death, along with that of Huragok Lighter Than Some, made Dadab attempt to kill Tartarus.
List of appearances