Anna was the illegitimate daughter of a male Argentinian priest and a young Irish missionary. She is born in County Kerry, Ireland. Her birth brought scandal until her mutant powers of healing and limited telekinesis manifest. This generates a group of worshipful followers, which is where her code name originates from. Anna also develops the power to change into a gaseous form.
Saint Anna was a member of the mutant team X-Force, and given that she was devoutly Christian, she was one of the few members to join the team for purely altruistic reasons. Her first time in public with the team gets them attacked by the former members of X-Force, who dislike the methods of the new group. Saint Anna hangs back and offers to cure the perceived pain of Anarchist, offering to move inside him.
Her first mission, as detailed by the one-armed Coach involves rescuing a young child named Paco Perez being mistreated. Paco's body has the potential for the cures to many diseases. He claims it is for the boy's own well being and safety, but as would be revealed later, he only wants Perez so American forces can exploit him.
The mission doesn't go well. The team is attacked right away and Bloke is killed defending their contact. U-Go Girl teleports the team into the cell holding Perez. Military forces attack and since Paco is attached to so many machines, he cannot instantly be removed. The team fights a delaying action and Saint Anna is shot in the stomach..
The team escapes, Paco in tow. Mister Sensitive promises to find the father she never knew and give him her mother's ring. Anna dies and disintegrates. Her ashes enter Mister Sensitive. Guy keeps his word and "sneezes" her ashes around her father. Miraculously, this gives the former priest memories of Saint Anna's entire life, which leaves him overjoyed. Paco, despite the team's orders, is left in the priest's care.