In Act IV Scene iii, how does Juliet show herself to be a vulnerable character in her soliloquy? Pointing out quotes would be helpful. :)
She is about to fake her own death. There are many things that go through her head right now. What if the potion doesn't work? Will she have to go through with the wedding to Paris? What if the potion is too much for her and kills her? Will she never see Romeo again? Or is the Friar trying to kill her to cover up his mistake in marrying them without parental consent? All of these questions go through her mind. These questions show her vulnerability. She is after all just a child. She is barely a teenager. All of these actions--even getting married on her own--are all adult choices. She is too young to have to deal with all of them on her own. However, she is alone and feels she has few in her life she can trust.
Some quotes from the scene can back up her feelings of vulnerability. The first shows she needs comforting. The next two ask the questions that bother her:
"I have a faint cold fear thrills through my veins,
That almost freezes up the heat of life:
I'll call them back again to comfort me"