Gertrude and Ambiguity
Gertrude is most definitely a central figure in the play – Hamlet spends a whole lot of time dwelling on her incestuous marriage to Claudius – but her character is also pretty ambiguous. Was she having an affair with Claudius before the death of Old Hamlet? Does Gertrude know that Claudius killed her former husband? Why does she drink the poisoned wine her husband has prepared for her son? Does she know it's poisoned? Or, is she just really thirsty? Like so many other issues in Hamlet, Shakespeare leaves these questions unanswered. But, that doesn't mean we can't or shouldn't think about them anyway.
Big Old Cheater?
First things first. Was Gertrude stepping out with Claudius while Old Hamlet was still alive? The Ghost all but accuses her of adultery and incest when he calls her new husband, Claudius, "that incestuous and adulterate beast" (1.5.9). Okay, it seems clear Gertrude's guilty of adultery (cheating on one's spouse) right? Not so fast. In Shakespeare's day, "adulterate" could refer to any sexual sin (like incest), not just cheating. But, if you really want to argue that Gertrude's a big old cheater, be sure to check out the ghost's emphasis on the marriage "vow" he made to Gertrude (1.5.9).
Next question. Did Gertrude know her late husband was murdered by her new man? Again, we can argue either way. For those of you who want to say "No way!" you'll want to note that the Ghost never accuses Gertrude of murder in Act I, scene iv. Also, Gertrude seems pretty surprised when Hamlet accuses her of "kill[ing] a king and marry[ing] with his brother" (3.4.10). On the other hand, we could also argue that Gertrude is surprised because, well, she's been caught. Take your pick.
Finally, does Gertrude know she's chugging poisoned wine in the play's final act? You know the answer to this one,...