Here is the full list of all 25 Bastard Bonds achievements.
Destroy Leviathan and escape from Lukatt
Pacify Leviathan and conquer Lukatt.
Have an audience with a Demon Lord.
Sooth the fears of a monster.
Attend a friend's second wedding.
Find the acoustic sweet spot.
Disrupt a shady business operation.
Restore the proper flow of time.
Get left out of a game.
Decide who wins the contest.
Teach a friend some proper manners.
Rescue a hapless friend.
Reconnect the estranged couple.
Save Captain Logus.
Obtain the darkest arcane power.
Forge the brothers' emblems together.
Complete the Eccentric Smith's project.
Don't let anybody sleep on the floor.
Second-Guess a friend's history.
Ruin a powerful weapon.
Obtain a Devil Adonis.
Earn someone's trust.
Let someone down.
Vent about past regrets.
Tear open an old wound.