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