(Spoilers)
 
 
Psalm wanted to be someone who could supply the troops on the front lines, but ended up serving as a soldier. She showed exceptional skill on the battlefield and became a member of Macintosh’s Marauders. She did not enjoy killing and was shown as being remorseful over the fact she had to kill. Psalm was ultimately the one who shot Big Macintosh during the battle at Shattered hood Ridge, believing Princess Celestia would be better off dead than a captive of the zebras. The day after Big Macintosh’s death, Psalm withdrew from the Marauders and worked as a sniper for Luna and Goldenblood.
 
During the last day, Psalm was ordered to carry out Project Partypooper which involved the assassinations of the Ministry Mares, though she only succeeded in killing Pinkie Pie before Manehatten was destroyed by a balefire bomb. Returning to base, Psalm discovered Garnet was the one who ordered her to carry out the task instead of Luna. Psalm shot Garnet but left her alive rather than mercy killing her, and ventured to Maripony to kill Twilight Sparkle.  
She failed her mission and was finally absorbed into the goddess and unity. Later on she was deposited into Lacunae who was where the Goddess would place all memories and emotions she didn’t want and was the reason that Lacunae decided to stay in the hoof in a sort of exile.
 
After the destruction of the goddess, Psalm survived to become one of the free Alicorns and is fighting to free Hoofington from the tyranny of the Legate and the brood.
 
Fallout Equestria was written by kkat and Project Horizons is written by Somber