Swear Blood Brotherhood

is_available = mpo_valid_for_blood_brotherhood_trigger = yes
trigger_if = {
	limit = {
		is_ai = yes
	}
	is_at_war = no
	is_imprisoned = no
	has_blood_brother = no
}
is_shown = scope:actor = {
	NOT = {
		var:had_mpo_temujin_flavor_0020 ?= scope:recipient
	}
}
scope:recipient = {
	mpo_valid_for_blood_brotherhood_trigger = yes
	NOT = {
		this = scope:actor
	}
}

As written in game/common/character_interactions/09_mpo_interactions.txt.

mpo_can_be_blood_brothers_trigger = {
	CHARACTER_1 = scope:actor
	CHARACTER_2 = scope:recipient
}
scope:actor = {
	is_imprisoned = no
	is_incapable = no
}
scope:recipient = {
	is_imprisoned = no
	is_incapable = no
}

As written in game/common/character_interactions/09_mpo_interactions.txt.

on_accept = scope:actor = {
	show_as_tooltip = {
		set_relation_blood_brother = scope:recipient
	}
	custom_tooltip = blood_brother_alliance_actor_alliance_tt
	custom_tooltip = blood_brother_actor_gains_hook_tt
	if = {
		limit = {
			scope:recipient = {
				mpo_blood_brother_august_trigger = {
					OTHER_BROTHER = scope:actor
				}
			}
		}
		if = {
			limit = {
				scope:actor = {
					government_has_flag = government_is_nomadic
				}
			}
			custom_tooltip = blood_brother_august_nomadic_modifier_tt
		}
		else = {
			custom_tooltip = blood_brother_august_modifier_tt
		}
	}
	if = {
		limit = {
			scope:recipient = {
				mpo_blood_brother_warrior_trigger = {
					OTHER_BROTHER = scope:actor
				}
			}
		}
		custom_tooltip = blood_brother_warrior_modifier_tt
	}
	if = {
		limit = {
			scope:recipient = {
				mpo_blood_brother_clever_trigger = yes
			}
		}
		if = {
			limit = {
				scope:actor = {
					government_has_flag = government_is_nomadic
				}
			}
			custom_tooltip = blood_brother_clever_nomadic_modifier_tt
		}
		else = {
			custom_tooltip = blood_brother_clever_modifier_tt
		}
	}
	if = {
		limit = {
			scope:recipient = {
				mpo_blood_brother_loving_trigger = yes
			}
		}
		custom_tooltip = blood_brother_loving_modifier_tt
	}
	if = {
		limit = {
			always = scope:common_enemy
		}
		custom_tooltip = blood_brother_foe_modifier_tt
	}
}
scope:recipient = {
	show_as_tooltip = {
		set_relation_blood_brother = scope:actor
	}
	custom_tooltip = blood_brother_alliance_recipient_alliance_tt
	custom_tooltip = blood_brother_recipient_gains_hook_tt
	if = {
		limit = {
			scope:actor = {
				mpo_blood_brother_august_trigger = {
					OTHER_BROTHER = scope:recipient
				}
			}
		}
		if = {
			limit = {
				scope:recipient = {
					government_has_flag = government_is_nomadic
				}
			}
			custom_tooltip = blood_brother_august_nomadic_modifier_tt
		}
		else = {
			custom_tooltip = blood_brother_august_modifier_tt
		}
	}
	if = {
		limit = {
			scope:actor = {
				mpo_blood_brother_warrior_trigger = {
					OTHER_BROTHER = scope:recipient
				}
			}
		}
		custom_tooltip = blood_brother_warrior_modifier_tt
	}
	if = {
		limit = {
			scope:actor = {
				mpo_blood_brother_clever_trigger = yes
			}
		}
		if = {
			limit = {
				scope:recipient = {
					government_has_flag = government_is_nomadic
				}
			}
			custom_tooltip = blood_brother_clever_nomadic_modifier_tt
		}
		else = {
			custom_tooltip = blood_brother_clever_modifier_tt
		}
	}
	if = {
		limit = {
			scope:actor = {
				mpo_blood_brother_loving_trigger = yes
			}
		}
		custom_tooltip = blood_brother_loving_modifier_tt
	}
	if = {
		limit = {
			always = scope:common_enemy
		}
		custom_tooltip = blood_brother_foe_modifier_tt
	}
}
show_as_tooltip = {
	if = {
		limit = {
			scope:recipient = {
				is_acclaimed = yes
				is_knight_of = scope:actor
			}
		}
		scope:recipient = {
			if = {
				limit = {
					scope:actor = {
						prestige_level >= 4
					}
				}
				custom_tooltip = recipient_accolade_major_glory_tt
			}
			else_if = {
				limit = {
					scope:actor = {
						prestige_level >= 2
					}
				}
				custom_tooltip = recipient_accolade_medium_glory_tt
			}
			else = {
				custom_tooltip = recipient_accolade_minor_glory_tt
			}
		}
	}
}
add_clan_unity_interaction_effect = {
	CHARACTER = scope:actor
	TARGET = scope:recipient
	VALUE = minor_unity_gain
	DESC = clan_unity_oath_of_true_friendship.desc
	REVERSE_NON_HOUSE_TARGET = no
}
if = {
	limit = {
		always = scope:common_enemy
	}
	scope:actor = {
		make_blood_brother_save_common_enemy_effect = yes
	}
}
hidden_effect = {
	scope:recipient = {
		save_scope_as = blood_bro
	}
	scope:actor = {
		set_relation_blood_brother = {
			reason = sworn_blood_brother
			target = scope:recipient
		}
		trigger_event = mpo_interactions_events.0006
	}
	clear_saved_scope = blood_bro
	scope:actor = {
		save_scope_as = blood_bro
	}
	scope:recipient = {
		trigger_event = mpo_interactions_events.0006
	}
}
on_decline = scope:actor = {
	send_interface_toast = {
		type = event_toast_effect_bad
		title = make_blood_brother_interaction.decline.actor.tt
		left_icon = scope:recipient
		add_stress = minor_stress_gain
	}
}
scope:recipient = {
	send_interface_toast = {
		type = event_toast_effect_neutral
		title = make_blood_brother_interaction.decline.recipient.tt
		left_icon = scope:actor
		scope:actor = {
			add_opinion = {
				target = scope:recipient
				modifier = hurt_opinion
				opinion = -20
			}
		}
	}
}
hidden_effect = {
	scope:recipient = {
		if = {
			limit = {
				NOT = {
					has_relation_potential_rival = scope:actor
				}
			}
			random = {
				chance = 20
				set_relation_potential_rival = scope:actor
			}
		}
	}
}
add_clan_unity_interaction_effect = {
	CHARACTER = scope:actor
	TARGET = scope:recipient
	VALUE = minor_unity_loss
	DESC = clan_unity_declined_true_friendship.desc
	REVERSE_NON_HOUSE_TARGET = no
}

As written in game/common/character_interactions/09_mpo_interactions.txt.