John Wilkes Booth gathered a group of people to kidnap the president and ransom him to thousands of Confederates. These people included John Surrat, Lewis Powell, David Herold, and a few others. "It was as though a great star of the modern age picked you, a completely anonymous, unknown person of no status, no wealth, no importance, a great star picks you to be his confidante, his pal, his companion, to travel with, to dine with, drink with" (The Assassination...). The conspirators did not join the plan because they hated Lincoln or his beliefs, but because they loved John Wilkes Booth---he gave them something they had been denied and did not currently posses.
Lewis Powell was to murder the secretary of state, William Seward. George Atzerodt's job was to murder the vice president, Andrew Johnson. "Booth of course reserved the greatest act for himself. He would perform the Lincoln assassination solo" (The Assassination...)
Booth carried out the avenging of the South and murdered Lincoln in front of everyone at the theatre. Lewis Powell severely injured Seward at his home and failed to kill him then and there. And George Azterodt was too afraid and never carried out his plan.
They decided to commit acts of treason out of a sense of belonging and interpersonal fulfillment, revealing violence against others resulting from a motivation to feel empowered and wanted.