Young Lucius flees from his aunt Lavinia, fearing that she is crazed. In fact, she merely wants to get to the book he is carrying, Ovid's Metamorphoses. She turns through its pages until she reaches the story of Philomela and Tereus (Tereus rapes his sister-in-law Philomela and then cuts off her tongue so that she cannot reveal the crime), which she shows to her father and uncle to indicate what has been done to her. Marcus urges her to carve the name of the culprits in the sand. Holding the staff with her mouth and guiding it with her stumps, she writes, "Stuprum[Latin for rape] -- Chiron -- Demetrius." They all kneel and take a vow to not rest until the treacherous Goths have been made to pay with their blood.
On Titus's orders, Young Lucius delivers weapons from his armory to Chiron and Demetrius, along with a scroll bearing a quotation of Horace, stating, "The man of upright life, and free from crime, has no need of the Moore's javelins or arrows." The insult is lost on the young Goths, but Aaron notes it. Then a nurse enters with a blackamoor child, the bastard son of Tamora and Aaron, and asks that Aaron kill it before it brings shame to the empress. Aaron roars to the defense of his son, and claims that black is the best color because it does not deign to take on any other colors. He kills the nurse to keep the secret of the child safe, then decides to return to the Goths so that he may protect his son.
Both these scenes show how words are used as tools and weapons in the play. In the dramatic disclosure of Lavinia's rape we see the climax of the concept of her body as text. Her signs are too confusing for her father, and uncle and she must resort to the words of Ovid to tell the truth. In essence, words, and a knowledge of the myths they spin, constitute a strength because they allow the characters to communicate, and thereby to attack, in a world of deceit. In a sense, if heroism is based on anything in this play, it is based on wit and knowledge of the classical texts. This theme is furthered in the following scene where Young Lucius delivers weapons as "gifts" to Chiron and Demetrius, along with a message that says upright men have no use for weapons. It is the succinct quote from Horace that transforms the seeming gifts into an insult. Because Tamora's sons do not catch the implication they are shown to be barbaric creatures. However, because Aaron catches the insult he demonstrates that he is indeed a formidable foe who at least functions at the same level of wit as Titus.
In Aaron's reaction to the birth of his son, the play deals for the first time with the issue of his race. In defending his son, Aaron defends the color that has for so long caused him to be ostracized: "Coal-black is better than another hue / In that it scorns to bear another hue" (IV.ii.99-100). In these lines we gain a better sense of Aaron as the victim of a racially biased society, and a possible insight as to why he is set on a path of evil. His immediate attachment to his son, his new and only bond with the rest of the world, reveals just how alone and unallied he has been throughout the play. Although he has played lover to the queen, coach to her sons, and foe to the Andronici, he has committed his acts solely for his own pleasure. In a sense, there is honor to what he says about the honesty of the black hue: it is one thing that, by its nature, remains itself. While all the other characters are constantly in disguise, shifting alliances for their own interests, Aaron wears his villainy on his sleeve, and is loyal, at least, to that.
This scene is often used to make comparisons between Aaron, Tamora, and Titus in the matter of parenthood. Tamora herself wants her lovechild with Aaron eliminated, while Titus has killed some of his children with his own hands. In comparison, Aaron's fierce love for his child seems to mark him as a much better parent than those we have thus far seen.