The Fate of Iberia achievement

History's Best Friends

Sleep with your best friend while having the Ritualized Friendship Cultural Tradition.

Conditions as the game checks them

Possible decides whether the achievement can still be earned in a run; happened is the check that unlocks it (common/achievements/_achievements.info).

Unlocks when (happened) (4 lines of game script)

custom_description = {
	text = fp2_historys_best_friends_trigger
	exists = global_var:fp2_historys_best_friends_achievement_unlocked
}

As written in game/common/achievements/fp2_achievements.txt.

The file gives no “possible” condition for this one.

Source: game/common/achievements/fp2_achievements.txt, game/common/achievement_groups.txt and the English localisation, Crusader Kings III 1.20.0.3. Unlock share: Steam Web API, 2026-10-02.