This thought was brought up after reading Pariah, a very, very good short story from Halo: Evolutions. In Pariah, a Spartan named Soren is brought into the SPARTAN-II program. His life before the program was traumatizing for him. He nearly kills his step-father after his mother dies and his step-father hides the body in a closet. His father later dies, and Soren could have stopped it. When he is brought into the SPARTAN-II program, he is unlike any other Spartan. He is given choices on most things (like joining the program, going through augmentations). He chooses to join and go through the augmentations. Unforntunetly, he is heavily deformed by the augmentations. He becomes rejected by sociaty, not being able to go into combat, getting a simple job of desk duty. A technician named Partch does not ignore him, he almost becomes a good friend. Partch speaks of a revolution, and Soren listens.
Partch is secretly a Insurrectionist. Months after they first meet, he tells Soren that they will defect from the UNSC, but he wants to "get" a "souvenir" first. When they try, they are stopped by a Spartan named Randall (who is my favorite Spartan). Randall nearly stops them from stealing the "souvenir", but they escape in a Longsword. They are shot down.
This brings up a strange subject. What if Spartans DID rebel? Would the Insurrection be better then the UNSC? Would they be equal? Would the UNSC crumble, or would ONI just press a button to shut down the suits, killing the people inside the Spartan's armor? Personally, here is WHY I think they would/could have rebelled.
Remember when John-117 wanted to pick up the Spartans that were on Reach, in Halo: The Fall of Reach? What if John stole a dropship and tried to pick them? Would the battle have shifted, or would John be in the Micro Dyson Sphere with Kelly and Dr. Halsey and company? There are many "What if..."s in the Halo series, but one thing is clear. Halo would be very, very different.
-Peace, Scot 113