Brute Buddies
From Halopedia, the Halo wiki
This glitch can only be performed on Halo 2.
Play the level Great Journey on any difficulty. When you're in the Banshee and Sergeant Johnson is in the Scarab, fly to the ground near the Control Room and wait for a Banshee to fly down to you. Hijack it. The Brute will fall out and land on the ground but he will not die. Fly down and get close to the Brute and he will calmly walk toward you and follow you wherever you go. Even though he is making berserker yells he will not attack you. If you do the same with others they too will follow so you can have a Brute pack follow you wherever you want. When you kill one however they will become furious again and attack you, so do not kill them.