In France, Isabella speaks to Prince Edward. She laments that the French king and nobles have failed to support her. The Prince urges her to return to Edward II and trust in his ability to win his father's favor. Isabella, however, says that she and her husband now “jar” together too much to ever be reunited, and wonders aloud what will become of her.
Because Prince Edward will eventually emerge as the King of England, the play works to establish his legitimacy early on by having him demonstrate his allegiance to Edward II. Because Edward II is both Prince Edward's father and the crowned king, the Prince's declaration serves as a double display of loyalty to both family and the rule of law. The Prince's youth helps in this respect, because while it is true that Edward II has himself arguably flouted the law as king, his son is at this point too young to be implicated in Edward's actions or possibly even to fully understand them.
Sir John, a nobleman from modern-day Belgium, enters and greets Isabella. He invites her and Prince Edward to come with him to his home in Hainault, where they can “shake of all [their] fortunes equally.” Prince Edward agrees, provided Isabella does as well, because he is determined not to leave her side until he is old enough to challenge Spencer Junior. Isabella, for her part, remarks proudly on how hopeful her son makes her and agrees to go to Hainault. At that moment, however, she notices Kent and Mortimer Junior entering.
Prince Edward's remarks here continue to demonstrate his worthiness as a successor to the English throne. Despite his devotion to his family, it is clear that he will not tolerate behavior that threatens the welfare of the kingdom: his remarks about Spencer foreshadow his ultimate execution of Mortimer Junior, who similarly functions as the favorite of a member of the royal family (i.e. Isabella).
Isabella is surprised to see Kent and Mortimer Junior, whom she had heard were dead. Mortimer, however, explains that he is "reserved for better hap," and has escaped in order to help crown Prince Edward the king of England. This upsets the Prince but pleases Isabella, though she hastens to add that their attempts to find allies in France have been unsuccessful. Mortimer reassures her, saying that “right makes room / Where weapons want”: although he admits that Warwick and Lancaster are dead, he assures her that they still have friends in England. Kent interjects that he wishes peace were restored and Edward II “reclaimed” (i.e. subdued), but Mortimer Junior brushes this aside, arguing that Edward can only ever be made to accept their terms “by the sword.”
Kent's words in this scene are an early sign that his allegiance is once again shifting. Mortimer interprets his wish to see Edward "reclaimed" to mean that Kent would like to see his brother change his ways but remain king—something Mortimer insists is impossible. Mortimer instead feels that war is inevitable, and assures his listeners' that the rebels will prevail: as Edward did earlier, Mortimer associates the justice of his cause with certain victory. This speaks to Mortimer's belief that his life has so far been spared because he is "reserved for better hap" (i.e. fortune). At this point in the play, Mortimer believes that an individual's ultimate fate hinges on his worthiness. This eventually proves to be untrue, since "fortune's wheel" will eventually cast down nobles, commoners, heroes, and villains indiscriminately.
Sir John urges Kent and Mortimer Junior to accompany Isabella to Hainault, where they will be able to raise both money and an army. Prince Edward predicts that Edward II will nevertheless defeat them, and Isabella scolds him for discouraging their allies. Kent and Mortimer, however, accept Sir John's proposal and praise him for helping the English Queen and nobles in a time of need.
Once again, Prince Edward's warning seems to stem at least in part from familial loyalty: his faith in his father's ability to defeat the rebels, though misplaced, helps establish the Prince as an honorable character.