force_assign_character_to_random_agent_slot_effect

force_assign_character_to_random_agent_slot_effect = {
	$SCHEME$ = {
		random_scheme_agent_slot = {
			limit = {
				is_filled = no
				save_temporary_scope_as = slot_temp
				$CHAR$ = { is_valid_as_agent_in_slot = scope:slot_temp }
			}
			save_scope_as = valid_slot
		}
	}
	$CHAR$ = {
		force_add_to_agent_slot = {
			agent_slot = scope:valid_slot
			years = $YEARS$
		}
	}
}

As written in game/common/scripted_effects/00_scheme_scripted_effects.txt.