A recent article in JBL discusses the sexual use of slaves: Joseph A. Marchal, "The Usefulness of an Onesimus: The Sexual Use of Slaves and Paul's Letter to Philemon," JBL 130.4 (2011): 749-70. I have not read the article, though I am skeptical of the main thesis.
It did remind me, though, of an idea I had sometime back about Joseph in Potiphar's house. Now, a couple of times, Potiphar is called in Hebrew a saris (Gen. 37:36; 39:1), a word used in the Pentateuch only here and a little later in Genesis, in reference to Pharaoh's 'chief cupbearer' and 'chief baker' (40:2, 7). The word is used 42x in the Hebrew Bible: 9x in the Former Prophets (i.e., historical books), 2x in Chronicles; 12x in Esther; 3x in Isaiah; 5x in Jeremiah; and 7x in the first chapter of Daniel.
The NRSV splits its translation of saris between 'officer' (or some such) and 'eunuch', which is the way it renders it in 2Kings 9:32; 20:18; 23:11; every time in Esther and Isaiah; Jer. 34:19; 38:7; 41:16. On the other hand, the LXX consistently translates saris with the Greek eunouchos, opting for a different translation only a handful of times. In fact, twice (Gen. 37:36; Isa. 39:7) the LXX uses a different Greek word, spadon, that also means 'eunuch'.
The point of this review of the philological data is to say that when Potiphar is called a saris, almost all English translation render this 'officer', but an equally viable translation would be 'eunuch', and this was certainly the view of the earliest interpretation on record, the LXX. I believe that the main reason that English versions stay away from 'eunuch' in this context is because Potiphar is married, and it is thought unlikely that a eunuch would have a wife.
Actually, I think that provides an interesting reading to the story. We all know that Mrs. Potiphar comes off as rather sex-crazed, and this could be explained by the fact that she is married to a eunuch. But why would a eunuch get married? Well, he's a high-ranking public official, who needs to give the appearance of a wonderful home life. At least it's not hard to think of modern analogies to this (perhaps anachronistically) hypothesized situation. I believe I have come across this interpretation somewhere, but I can't remember where.
But I have never seen the suggestion that Joseph may have been purchased by Potiphar specifically to fulfill this need of his wife's. And that's where Marchal's article could help with supplying data for the sexual use of slaves in antiquity (though I understand that Marchal is looking specifically at a Greco-Roman context, not an ANE one). It is worth thinking about, anyway, whether Potiphar may have wanted to purchase this good-looking slave (39:7) to satisfy his wife, or even to raise up offspring to himself. Well, does it at least sound like something JSOT might print?
But yesterday my friend Nathan Daily pointed out that if I'd actually read the text, I'd see that Joseph said to Mrs. Potiphar quite clearly that Potiphar has withheld her from him (Joseph) precisely because she is his (Potiphar's) wife (39:9).
Too bad. That seems like it kills my interpretation. I only see two options for retaining it. Perhaps Joseph was unaware of Potiphar's plans for him, and Potiphar counseled his own wife to seduce the handsome slave. Now, that really sounds like JSOT material. Or, maybe the final redactor of Genesis has attempted to cleanse the story of these impious elements through some crafty editorial work, but he failed to do his job well enough that we can't recover the original form of the story. And, of course, we do that by the oft-used scholarly technique of 'making-it-up'.
Now that sounds like I've got something for VT or ZAW. But I think I'll leave the matter alone. Dear readers, feel free to develop the idea yourselves, but perhaps you'll want to start with a conference paper.