After Harry and Hermione used the time turner to save their past selves, help Sirius and Buckbeak escape, they have returned to the hospital wing to rest for the night. As they change into pyjamas and climb into their beds.
"Hey Harry," Hermione called out "after seeing you conjure that Patronus charm to defend against all the dementors, I think I found the happy memory I need to conjure mine too." "Really!" Harry burst out. "Yeah, now watch... Expecto Patronum!". As Hermione speak the enchantment while flickering her wand, a silvery blue spark shoot off from the tip of her wand. As it flies it expand, first into a cloud and then it took shape. It's a fawn! Harry thought to himself, he can't help it but cast the same charm. As their Patronuses dance together in the air and mingle, Harry can't help but smile at Hermione. "Would you look at that! Mine a stag and yours a fawn, both of our Patronuses have something to do with deer!" With that happy though, Harry fell asleep before his head could even hit the pillow.
"Goodnight Harry...", Hermione said in a whisper. "Lumos" Hermione mumured while pulling a book out of her bag. It was Book of Spells by Miranda Goshawk, as she flips the page, she periodically looked up at Harry and smiled to herself then immediately looked back down, hiding her blush using the dark of the night. Finally, Hermione stopped flipping on the page for Patronus Charm. "Harry did you know," Hermione read out loud quietly, "Corporeal Patronus, a guardian which generally takes the shape of the animal with whom they share the deepest affinity. You may suspect, but you will never truly know what form your Patronus will take until you succeed in conjuring it." She turned her head slightly to look at Harry in his sleep.
When Harry, Ron, and Hermione left the hospital wing at noon the next day, it was to find an almost deserted castle. The sweltering, heat and the end of the exams meant that everyone was taking full advantage of another Hogsmeade visit. They wondered the grounds of Hogwarts given Ron's injury and Harry still not having the permission to go to Hogsmeade. Harry tried to teach Ron the Patronus Charm to see if the trio all had something to do with deer, but found no luck. When Ron heard that both Harry and Hermione were able to do it, he was excited to see them cast their corporeal Patronus.
After meeting Hagrid along the way and learning about Professor Lupin's departure, Harry rushed to see the man who in a way saved his life. After having a conversation with Moony, Harry learned the past of his father and his friends. Later Dumbledore came to see Professor Lupin take his leave, and gave Harry a few words of thoughts. As Dumbledore left the Defence Against the Dark Art office, leaving Harry to his very confused thoughts, Harry recalled the words of Dumbledore and the events of last night. "You think the dead we loved ever truly leave us?... How else could you produce that particular Patronus? Prongs rode again last night.", "If my Patronus is a stag because my dad was Prongs, why is Hermione's Patronus a fawn? "