progress_towards_rival_effect

progress_towards_rival_effect = {
	$CHARACTER$ = { save_scope_as = target_char }
	# Do we merit an actual rivalry?
	if = {
		limit = {
			# We don't care between low-tier chars.
			scope:target_char = { highest_held_title_tier > tier_barony }
			# Are they low-tier themselves or more than two tiers below the target?
			OR = {
				highest_held_title_tier <= tier_barony
				highest_held_title_tier <= {
					value = scope:target_char.highest_held_title_tier
					subtract = 3
				}
			}
			# If they are then they must...
			NOR = {
				# ... be related to the target...
				is_close_or_extended_family_of = scope:target_char
				is_consort_of = scope:target_char
				# ... or be heir to someone within social spitting distance of the target.
				any_heir_title = {
					tier >= {
						value = scope:target_char.highest_held_title_tier
						# So if they're feuding with an emperor, then they must be heir to at least a duchy.
						subtract = 2
					}
				}
			}
		}
		# Now, set grudge if we could already set it.
		if = {
			limit = {
				NOT = { has_relation_grudge = scope:target_char }
			}
			if = {
				limit = {
					exists = scope:relationship_reason_involved_character
					exists = scope:relationship_reason_province
				}
				set_relation_grudge = {
					reason = $REASON$
					target = scope:target_char
					involved_character = scope:relationship_reason_involved_character
					province = scope:relationship_reason_province
				}
			}
			else_if = {
				limit = {
					exists = scope:relationship_reason_province
				}
				set_relation_grudge = {
					reason = $REASON$
					target = scope:target_char
					province = scope:relationship_reason_province
				}
			}
			else_if = {
				limit = {
					exists = scope:relationship_reason_involved_character
				}
				set_relation_grudge = {
					reason = $REASON$
					target = scope:target_char
					involved_character = scope:relationship_reason_involved_character
				}
			}
			else = {
				set_relation_grudge = {
					reason = $REASON$
					target = scope:target_char
				}
			}
		}
		# Otherwise, increment raw opinion.
		else = {
			add_opinion = {
				target = scope:target_char
				modifier = grudge_opinion
				opinion = -20
			}
		}
	}
	#If potential rival, set rival!
	else_if = {
		limit = {
			has_relation_potential_rival = scope:target_char
			can_set_relation_rival_trigger = { CHARACTER = scope:target_char }
		}
		if = {
			limit = {
				exists = scope:relationship_reason_involved_character
				exists = scope:relationship_reason_province
			}
			set_relation_rival = { 
				reason = $REASON$ 
				target = scope:target_char 
				involved_character = scope:relationship_reason_involved_character 
				province = scope:relationship_reason_province 
			}
			if = {
				limit = {
					this.involved_activity ?= {
						has_activity_type = activity_playdate
					}
				}
				this.involved_activity ?= {
					add_activity_log_entry = {
						key = activity_generic_rival_log
						tags = { bad }
						score = 10
						character = prev
						target = scope:target_char
					}
				}
			}
		}
		else_if = {
			limit = {
				exists = scope:relationship_reason_province

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