Hermione takes over the watch at midnight. Harry's dreams are disturbing, so he gets up and suggests they move on. Hermione is thrilled to go somewhere more sheltered from the snow, and she notes that she keeps hearing people outside their protections. Harry stares at the silent Sneakoscope and they decide to Disapparate under the Cloak. They arrive in the Forest of Dean and Hermione sets up the tent. They remain for two days while Harry recovers from his brush with Voldemort, who seems somehow closer now. Harry insists on taking the night watch and tries hard to stay awake. A bright silver doe walks out of the trees, gazes at him, and then turns and walks away.
Voldemort feels closer because, on some level, both Hermione and Harry feel betrayed: Godric's Hollow was, in both of their minds, supposed to hold answers and yet, all they got was Voldemort. This sense suggests that Harry did expect too much from finding his parents' graves, and it suggests that he wanted answers from the dead—when graves exist more for the living to find peace and a sense of comfort, not for the dead themselves.
Harry hesitates and then follows the doe. The doe suddenly disappears and Harry lights his wand. There's nothing alarming around him, but he notices a frozen pond with the sword of Gryffindor lying at the bottom. Harry wonders how he, the sword, and the doe all converged on this place. He tries to Summon the sword, asks for help, and sighs when he decides he has to dive for it. Harry strips to his underwear, blows a hole in the ice, and wades in. He dives down but as soon as he grabs the sword, the chain of the Horcrux tightens around his neck. He loses consciousness and then comes to on the bank, the Horcrux off of his neck. Ron asks Harry incredulously why he didn't take the Horcrux off first.
The doe and discovering the sword—as well as Ron's reappearance—make it clear that someone out there is helping the trio figure things out. This shows Harry that he needs to continue to trust his greater community to help him, even when he doesn't explicitly ask for it. Saving Harry from the murderous Horcrux allows Ron to begin to redeem himself (in addition to the act of returning to his friends being somewhat redemptive). Ron can now hope to define himself in terms of his choice to return, not his choice to leave.
Harry dresses and stares at Ron, wondering if he's real. Ron says he didn't cast the doe; he thought it was Harry's Patronus. Ron says he's back if Harry wants him, and then offers the sword to Harry. He explains that he'd been looking for them in the forest for a while when he saw Harry following the doe. Ron points to where he thought he saw something move and Harry inspects the spot, but there's nothing there. They decide that whoever cast the Patronus put the sword in the pond, and they decide to destroy the Horcrux immediately.
Though Harry and Hermione's suspicions about someone in the woods was clearly founded, given that they likely heard Ron, it's telling that this "intruder" turned out to be a friend. With this, the trio continues to acquire evidence that they possibly don't need to be so suspicious, and that there's help out there if they're willing to look for it.
Harry leads Ron to a flat stone and insists that Ron destroy the Horcrux. He somehow knows that Ron needs to do it, but Ron refuses. Ron finally agrees and Harry asks the locket to open in Parseltongue. It swings open to reveal an eye. Ron prepares to stab it, but it begins to speak to Ron, telling him in Harry and Hermione's voices that nobody likes him, that he's stupid, and that even Mrs. Weasley likes Harry better. It says that Hermione loves Harry. Harry shouts for Ron to stab and sees a glint of red in Ron's eyes. Ron brings the sword down and Harry whirls away. When he looks back, Ron is crying but the locket is destroyed.
Allowing Ron to stab the Horcrux will allow Ron to feel again like he's a useful and knowledgeable member of the trio. This is essentially a confidence building exercise for him, in which Ron is forced to face his demons in the Horcrux and choose to either listen to the Horcrux—and choose evil—or destroy it and choose his friends and the quest to kill Voldemort.
Harry quietly says that he loves Hermione like a sister and that they barely spoke while Ron was gone. Ron apologizes for leaving, they hug, and they head for the tent. Harry excitedly wakes Hermione, who approaches Ron and then begins punching and shouting at him. Harry conjures a shield between them as Hermione continues to shout at Ron. When she runs out of steam, Ron says that he wanted to come back as soon as he'd left, but he ran into Snatchers, gangs out to catch Muggle-borns for money. He managed to get away, but Harry and Hermione had already left when he returned to their campsite. Hermione spits that they ran into Voldemort and Nagini, ignoring Harry saying that Ron saved his life.
Hermione's reaction isn't unfounded—she needs to be able to trust Ron and believe that he's going to be there for them, something that he called into question when he left. However, Ron's choice to return suggests that he's more dedicated to their quest than Hermione might think. Now, the onus is on Hermione to choose to forgive Ron and accept him back into the fold, something that would allow her to demonstrate her maturity and acknowledge Ron's goodwill.
Hermione asks how Ron found them and Ron pulls out the Deluminator. He explains that, on Christmas, he heard Hermione's voice coming out of the Deluminator, and a ball of light appeared, floated inside of him, and he knew where to Apparate to. This is how he found them in this spot, and he and Harry tell her about the doe and destroying the Horcrux. Hermione inspects the Horcrux while Ron gives Harry an extra wand he stole from the Snatchers. Hermione climbs into bed and ignores Ron.
Ron's journey to come back to his friends shows that Dumbledore certainly believed in redemption—he gave Ron something that would allow him to redeem himself, should Ron decide to do something silly like leave. That Harry accepts Ron back so easily suggests that he understands this, and that he understands the power of giving Ron a second chance.