suitable_shieldmaiden_gaoler_trigger

suitable_shieldmaiden_gaoler_trigger = {
	#Must be a shieldmaiden.
	has_trait = shieldmaiden
	NOR = {
		#Filter out prisoners that the shieldmaiden would want to see freed.
		has_friendly_relationship_trigger = { CHARACTER = root }
		#And require that they don't hate their liege.
		has_relation_rival = scope:imprisoner
		#Make sure they don't really like root, in which case they'd let the escape slide.
		opinion = {
			target = root
			value >= high_positive_opinion
		}
		#Aaaaand the inverse for actually really hating their host, in which case they don't care about escapees.
		opinion = {
			target = scope:imprisoner
			value <= high_negative_opinion
		}
	}
}

As written in game/common/scripted_triggers/01_fp1_scripted_triggers.txt.