In Antigone, we have two sisters, Ismene and Antigone, who have lost their brothers, Eteocles and Polyneices, in battle. They are characterized by how they act in response to the following situation: Polyneices was fighting against Thebes, his home city, which was ruled by Creon. That makes him a traitor. Because he has betrayed his city, Creon decrees that his dead body will be left to rot in the open and not given the burial rites that will allow his spirit to rest.
One sister, Antigone, cannot abide by this. Against Creon’s orders, she wishes to give Polyneices' body its proper rites. Her sister, Ismene, is afraid of Creon and what will happen if she defies him, so she does not help. When Antigone performs the rites and is sentenced by Creon, Ismene then decides to say that she too broke Creon’s edict and deserved punishment:
I have done the deed, if she allows my claim, and share the burden of the charge.
Antigone, however, will not allow it:
Do not share my death nor claim deeds to which you have not put your hand; my death will suffice.
Ismene, by her actions and words is characterized as a well-meaning but indecisive character who is afraid to do what she believes is right in the first place, and then wants credit for the deed, even though it will result in her death afterward.