bp2_valid_hostage_offer_action_trigger

bp2_valid_hostage_offer_action_trigger = {
	# Context checks, e.g. alliance
	bp2_valid_hostage_action_shared_trigger = yes
	# Only care about actual threats
	has_any_cb_on = root
	save_temporary_scope_as = warden
	# Does not already have your hostage
	NOT = {
		any_warden_hostage = { home_court = root }
	}
	root = {
		# You have a hostage to offer
		any_close_family_member = {
			count >= 1
			bp2_valid_to_offer_as_hostage_trigger = { SENDER = root }
			save_temporary_scope_as = my_hostage
		}
		# Ensure Offer might be accepted
		is_character_interaction_potentially_accepted = {
			interaction = offer_hostage_interaction
			recipient = scope:warden
			secondary_actor = scope:my_hostage
		}
	}
	# Why Offer when you could Exchange?
	trigger_if = {
		limit = {
			# Only if they don't have your hostage already
			NOT = {
				any_home_court_hostage = { warden = root }
			}
			any_close_family_member = {
				bp2_valid_to_offer_as_hostage_trigger = { SENDER = scope:warden }
				save_temporary_scope_as = their_hostage
			}
		}
		NOT = {
			root = {
				is_character_interaction_potentially_accepted = {
					interaction = exchange_hostage_interaction
					recipient = scope:warden
					secondary_recipient = scope:their_hostage
					secondary_actor = scope:my_hostage
				}
			}
		}
	}
}

As written in game/common/scripted_triggers/05_bp2_hostage_triggers.txt.