Vardaman notices that the barn is burning and therefore that it "wasn't a barn now." Cash's foot turns black from the cement cast, while Jewel's back becomes red from the fire-induced burns. Dewey Dell rubs medicine on it, which then makes it also turn black.
In observing that the barn "wasn't a barn" any more, Vardaman applies his same vocabulary for expressing questions and thoughts about human (and fish) existence and mortality to the now destroyed barn.
Anse breaks off Cash's cast and his leg begins to bleed. Darl then asks Jewel if his back hurts. At some point, Darl leaves and the family asks where he is. Darl ends up lying next to Addie's coffin under the apple tree weeping. Vardaman fins Darl and comforts him by telling him that Jewel got the coffin out of the burning barn and so there is no need to cry. In his head, Vardaman repeats that he saw Darl do something the other night when he was looking where the buzzards go and that Dewey Dell said he should keep a secret.
The image of Darl crying beside Addie's coffin shows Darl in a state of vulnerability that he does not call attention to in his own narrations. Whether he weeps from guilt at trying to burn the coffin, grief about his mother's recent death, or about his failure to end their quest is unclear. It is clear that Darl's gift for expression and observation do not indicate simply that he is a fully detached character, as his words and actions do have their foundation in intense emotion.