In what sort of light are women portrayed and treated in Titus Andronicus?
There is not much that is subtle about this play, including the women characters. Many scholars consider it to be a very early play of Shakespeare's, and as such, doesn't reveal much of the deep and complex characterizations that would people his later plays. If you consider Lavinia and Tamora separately, they are two cliched representations of women, but also complete opposites.
Tamora is a masculine woman in her behavior who has put aside her more tender, feminine aspects to "run with the boys," which is probably necessary. She is, after all, her people's ruler. She matches wits with the powerful male figures in the play and is as invested in her own revenge plot as Titus is in his. She does have her moments of speaking out as a loving and caring mother, but given her actions in the play, it is hard not to read some attempt at manipulation in these pleas. At the end of the play, she is completely demoralized, being made to eat a pie that contains the chopped up remains of her dead sons, and is finally overtaken by the more powerful Titus in his thirst for revenge.
Lavinia, on the other hand, is, at first, the model of the good, obedient daughter. She seems content to marry her father's choice for her, even though she is betrothed to someone else. Yet, there is an interesting confrontation between Lavinia and Tamora, once Lavinia is married, that shows some spunk and life. At the end, however, Lavinia is a victim of the power-hungry characters around her (including Tamora). She has her tongue cut out, and this forced muting is a nice symbol of how little "voice" she has in what befalls her in this society.
This is not one of Shakespeare's more delicate or subtle plays, and in it, the female characters are nearly cartoon-ish in their extreme rendering as either completely power-hungry and driven to revenge (Tamora) or as a victim of circumstance, one who is prepared to assume her required role as second class citizen to the men around her (Lavinia).