Here is the full list of all 27 7th Sea: A Pirate's Pact achievements.
Sign the Charter of the Brotherhood of the Coast and become a pirate.
Get the captains of the Brotherhood of the Coast to help you attack Fort Freedom.
Use your royal favor to get assistance attacking Fort Freedom.
Bring the villain to justice in your homeland.
Repel the sea serpent in La Bucca.
Defeat Allende in La Bucca.
Romance Captain Peyton Redwing.
Destroy the octopus sea monster.
Help the defeat the crew of the Drachen's Wrath.
Romance Captain Maurice LaFleur.
Romance Lex.
Kill the sea serpent in La Bucca.
Save Christine's life.
Sacrifice Captain Redwing to save Christine's life.
Successfully walk the high tower in Aragosta.
Get the Mawons in Jaragua to help you attack Fort Freedom.
Defeat a giant shark to gain the Riroco's aid.
Take an Atabean Trading Company ship as a prize to gain the Riroco's aid.
Get the Riroco in the Rahuri Islands to help you attack Fort Freedom.
Get all the groups of the Atabean Sea to help you attack Fort Freedom.
Sneak into Fort Freedom without ever alerting the guards.
Join the Atabean Trading Company and betray your friends.
Convince Sigrid to give up by talking to her.
Defeat Sigrid in combat to force her to surrender.
Force Sigrid's guards to give up without much of a fight.
Capture Sigrid and bring her to justice.
Kill Sigrid for her crimes.