Suicide Grunts are specially chosen infantry with exaggerated aggressive tendencies. Each Grunt is fitted with an unstable plasma cell and detonator and given only one order: rush the assigned target and violently explode. They can be upgraded with new "recruits" and plasma lensing which increases their damage against structures and vehicles.
Truly aggressive and violent Grunts are rare, but without Covenant oversight or the environmental hazards of Balaho to cull them from the population, the number of aberrants has increased dramatically in thrall colonies. The Banished have adapted existing indoctrination protocols to turn the aggression and natural cleverness of these Grunts to their own violent purposes.