Achievements are archetypal tasks that provide some kind of tangible benefit after completion. You do not need to opt into an achievement, instead they can be claimed retroactively after accomplishing a task.
Battle Scars
Requirement - Get defeated by a critical hit and survive in 3 different encounters. Or get crit 3 times in the same combat and survive.
Reward - The scars you get from battle are deeply entrenched in your memory. Your memories of combats you have encountered cannot be magically removed.
By touching them, you can perfectly recall past events, as long as they happened in the thick of combat. Other creatures can touch your scars to share in the experience of the memory
Backstabber
Requirement - Murder 3 people you once considered allies, or who at thought you were an ally (before you turned on them). If you murder someone in a position of great power, like a powerful guild leader or king, it counts as 3.
Reward - You have a 6th sense for when people trust you. By observing how they react to your presence in a brief interaction (such as an introduction), you can tell whether they trust you, are indifferent towards you or if they distrust you.
Critical Pet
Requirement - Use stealth to initiate combat on a creature by patting its head 3 times. This pat can have no mechanical effect such as delivering a spell or attacking.
Reward - You unlock the "Pet" skill, usable for memes. It uses your stealth bonus. If you sneak up on a creature and pet their head (again, no additional mechanical effect), you establish dominance, giving you a +2 bonus to skills for the subsequent social or combat encounter. If a creature within reach is smaller than you, you can pet them as a free action 1/turn for no mechanical benefit (no save).
