Are Lady Macduff and her son sympathetic characters? Why or why not?
Lady Macduff and her son are absolutely sympathetic characters. First, Macduff has left his family alone in Scotland so that he can go to England and try to convince Malcolm to come back and overthrow Macbeth. He apparently did not even tell his wife that he was leaving, let alone why he was going. His wife, thus, says that "He wants the natural touch" because abandoning his family when a tyrant is on the throne seems like a very unnatural decision (4.2.11); he should want to protect them and stay with them.
In the previous scene, Macbeth has declared that he will "surprise" Macduff's castle and "give to th' edge o' th' sword / His wife, his babes, and all unfortunate souls / That trace him in his line" (4.1.172-174). He is so angry that Macduff has escaped him by fleeing to England that he has vowed to kill Macduff's entire family and even his servants in order to hurt him. This is what the messenger arrives to warn them of in the next scene. He advises them to flee immediately, but Lady Macduff has no where to go. "Whither should I fly?" she asks (4.2.81). In the next moments, a murderer rushes in to kill her and her son; it is an incredibly tragic end for this family.