After everyone he ever loved died at the hands of a FAZECLAN incident. He wanted revenge on those who made him feel those feels.
The death of everyone he loved caused Pepe to feel feels nobody has ever feeled. He learned the way of the gun and knife. He became the ultimate school shooter, every school he went to felt his wrath.
Tiglard, seeing his potential, brought Lord Pepe on board. Lord Pepe uses his tactics and marksmanship to help the team escape and plan.