Time to face the hard facts: Hagar's story is basically that of an abused woman. Three basic facts about Hagar make her, in the social world of Genesis, little better than a dirty, tossed-around rag:
Long story short: after Hagar has a kid with Abraham, Sarah freaks out and starts to abuse her: "Sarai dealt harshly with her" (16:6 NRSV). Hagar gets the heck out of Doge—smart lady—but then God tells her to go back. Yep, the deity's messenger says, "Return to your mistress, and submit to her" (16:9 NRSV). This is troubling, to say the least.
And sure enough, when she returns, there's more abuse. Now Sarah has her own son and she doesn't want Hagar's son competing for the inheritance. So Sarah uses her authority to demand of Abraham, "Cast out this slave woman with her son!" (21:10 NRSV). And once again, God is on her side.
In the end, God saves Hagar and her son, and he promises to make Ishmael a great nation just like Isaac. It looks like God's not totally deaf to Hagar's suffering. After all, Ishmael's very name recalls that the deity "has given heed" (Hebrew: sham'a) to her pain (16:11 NRSV). But still, that sure was a lot of pain and suffering to go through first.
What are we supposed to make of a God who sends a woman back to her abuser?