An exceptionally virtuous person
A holy person, especially one canonized by a church
Then the saint stopped speaking and looked around him.
Saint Among Sinners it's called.
I care even less if your brother writes Saint Among the Sinners or Sinner Among the Saints.
He can just change the title from Saint among the Sinners to Sinner among the Saints, The Life and Times of a Mine-Town Hooker.
He was a saint through and through for rubbing her back instead of seducing her.