Here is the full list of all 14 Serin Fate achievements.
Play as a Human!
Acquire a Royal Note.
Harvest some Fairy Dust.
Reel in a Spined Ling!
Mr Three's hidden...
Hew down a Magic Tree.
Restore the Fate "Stone".
Defeat a Drifter with the Moon Shard flowing...
Craft a Mythic Bar.
Reach 200 Max HP.
Defeat both Servants and then defeat Manith on Hard Mode.
Seeking secrets!
Play as a Serin!
Play as a Val!