A sympathetic character is a personage in a literary work with whom the writer expects the reader to identify and care for, if not admire. Such a character is Portia, the wife of Brutus. While she is not physically in Act IV, Portia becomes a presence in this act as her death is reported to Brutus, and later alluded to by him in his conversation with Cassius. Earlier in the play, in Act II, when the devoted wife of Brutus notices that her husband is agitated and deeply concerned about something, Portia entreats him to confide in her, but Brutus puts her off as there is a knock at his door, telling her she will "partake/The secrets of my heart" later.
In Act IV, Brutus has been at war for some time, and he has begun to regret having killed Julius Caesar as he wishes "Things done undone" (4.2.9). Surely his absence as well as the turn of events have greatly affected the loving Portia. When Brutus and Cassius talk in the tent, Brutus tells Cassius that Portia is dead from eating coals from a fire:
Impatient of my absence,
And grief that young Octavius with Marc Antony
Have made themselves so strong--for with her deat
That tiding came--with this she fell distract,
And [her attendants absent] swallowed fire.(4.3.169-173)
While this report of Portia's death certainly arouses the reader's/audience's sympathies, the dismissal of talking about her to Cassius by Brutus is also an act that elicits pity for Portia.