They are called the Poor Souls in Purgatory for a reason. It is because they are the souls of people who have died in a state of grace, but who are not able to enter heaven yet because they owe a debt of temporal punishment due for their sins which have been forgiven. The Poor Souls cannot pray, offer sacrifice, or give suffrages for themselves. There is nothing that they can do to merit any relief from the pains that they experience in purgatory. They are called the Church Suffering, and they covet the Holy Sacrifice of the Mass, our prayers, fasting, sacrifices, and almsgiving in atonement to help relieve their pain. Holy Mother Church exhorts us that when we offer our sufferings, united with the Passion of Christ, and apply it to the Poor Souls, that it may cause their relief or release and entrance into Heaven.