Besides Tobit, his wife Anna, their son Tobias, and Tobias' dog (notably the only positive mention of dogs in the Bible), the Book of Tobit also focuses on Tobias' cousin Sarah, who lives in Ecbatana, a city on the path of Tobias' journey. Sarah, it turns out, has been married seven times, but each marriage has lasted less than a day, as her husbands all die on their wedding night. Perhaps naturally, Sarah has been accused of being responsible for their deaths, but savvy readers will guess that she is actually innocent. The figure actually responsible for all these deaths is Asmodeus, the demon of lust. By coincidence, Sarah's prayer is heard at the exact same moment as Tobit's by the archangel Raphael. As such, Raphael's plan to help Tobias is secretly also a plan to help Sarah.
When Tobias and Raphael catch the fish from the Tigris, Raphael tells Tobias that the gall of this fish will cure his father's blindness, but by burning the fish's heart and liver, he can repel demons. Tobias doesn't realize the significance of this until they stop in Ecbatana, where Tobias meets his cousin Sarah for the first time and learns of her plight. Tobias and Sarah are married, and as expected, Asmodeus shows up on the wedding night. He is repelled by the fish vape and bound in the desert by Raphael.
