Game of Thrones:
Season 5 | 6
Unella is described as big-boned with callused hands and a scowling homely face.
A Feast for Crows
Septa Unella is one of the septas assigned to get a confession out of Queen Margaery Tyrell; the queen confesses that she wants to claw Unella's eyes out. After Queen Regent Cersei Lannister is arrested, Unella becomes her confessor as well.
A Dance with Dragons
Unella continues to be one of the holy septas who visit Cersei every hour of the day or night asking her to confess. During one visit Cersei relents and tells Unella she wishes to confess her sins to his High Holiness, and Unella is one of the septas who bring her before the High Sparrow. When the High Septon allows Cersei visitors Unella summons Ser Kevan Lannister to see her. Unella is asked by the High Septon to stay and record Cersei's confession.
Septas Unella, Moelle and Scolera are part of the escort for Cersei as she completes her walk of atonement through the streets of King's Landing. Prior to doing so Unella has the queen shorn by silent sisters.
Only through confession and true repentance may our immortal souls be saved.—Unella to Cersei Lannister