Tobit - Circumstances of Sarah's affliction with Asmodeus

In the Book of Tobit, Sarah is placed in an rural setting in Ecbatana, pleading to the Lord for death after her numerous suitors have been smitten down by a demon called Asmodeus. Her predicament seems known to Tobias who voices his misgivings to Azarias (Raphael). There is quite an abundance of exegesis on this story, typically covering: its parallels with Job, its significance as an intertestamental text and influence on Christian thought in subsequent centuries. However, virtually no ink has been spilled on how and why Asmodeus began afflicting this girl in the first place. I have read a monograph on this book by Robert J. Littman, who sees fit to offer the following explanation: > A major folk motif is the taboo of virginity. The hero must win the > maiden through the defeat of a dragon, serpent or monster who guards > the virginity of the maiden. Often the hero is helped by gods or > magical figures who supply weapons or potions to help to defeat the > monster. We see this in the stories of Perseus and Andromeda, and of > Admetus and Alcestis, among many others. On the one hand, I realize we have little in terms of clues within the Book of Tobit itself; and I realize how often Greek/Roman novels/fictions are compared to texts of this period. On the other hand, applying folk legends and platitudes as such seems a bit crude. Perhaps we might do better by looking for possible inferences intertextually. The Old Testament seems to have associated the wilderness as a dwelling place for demons or where evil may have greater power (such an environment was also the setting for Matthew 4:1-11). This would be consonant with Ecbatana's geography; the name of the demon itself befits the milieu (as Mary Boyce points out in History of Zoroastrianism Vol III). Yet my "wilderness" anecdote theory seems to advance matters very little, it still seems crude. It still remains to be satisfactorily explained how/why/when it happened: - We have no indication that Sarah's family were heterodox or otherwise backsliding. - There are also no mentions as to how the demon first appeared to her and under what circumstances. Was he summoned by Sarah, or did one of Sarah's enemies afflict Asmodeus on her, or it may be that despite how evil Asmodeus is, he is still acting in accordance with the Lord in that he is helping to usher in the union of Sarah and Tobias who are predestined to be together

Question

Given the scarcity of explicit clues as to how or why Asmodeus afflicts Sarah, are there intertextual clues from elsewhere in the Canon that may help explain this, even if only marginally? (Note that in the case of Job, it is made clear that Satan is to test a man of good faith and principle, however in the case of Sarah, it is not explicit, it is merely implied. Though it is stated that Sarah comes from a clan that honors the Lord; though as we have seen elsewhere in the OT, parts of a family may be of pure faith while others succumb to idolatry).