Scarcely a day passed where Harry did not summon Prongs.
On days when the sun was shining, they walked around the grounds, Harry sometimes riding, Prongs sometimes stopping to graze at the green grass with his newly-solidified mouth.
Other times, they snuck around the halls of Hogwarts, little felt pads on Prongs' silver feet, to muffle the noise.
In the evenings, Harry curled up by the fire in the deserted Common room, leaning on Prongs' warm, steady back, basking on the sensations of calm and joy emanating from his Patronus.
And the more time they spent together, the more they understood each other, and the more they loved each other.
"I think I'm becoming addicted to you, Prongsie," joked Harry one day.
Prongs snorted, and turned his amused silver eyes on Harry.
But it wasn't a bad thing. It wasn't dangerous, like too much Felix Felicis or too many cheering charms. Because Prongs was Harry, Harry's soul, and they could never, never be separated.
"They think I'm traumatized," said Harry to Prongs. "From the graveyard. It's because I've been off with you so much lately."
Prongs merely nuzzled his warm silver nose into Harry a bit more.
"They don't understand, though," Harry mused. "They wouldn't understand how - important, how amazing you are to me. Hermione would say you're just a spell - she'd tell me it's unhealthy to get attached. Ron... well, Ron would get jealous. Again."
Prongs stood up, shaking his head. 'They wouldn't do that,' he seemed to say.
Harry continued, "You don't judge. You're always there, and somehow, I feel like you're more than just a spell..."
Prongs rolled his silver eyes, and playful antlers butted into Harry's side, insistent and friendly.
"It's a shame you can't talk..."
The empty corridor was not empty. One Harry James Potter was being dragged along by his Patronus, Prongs, mouth firmly clamped on his sleeve.
"Prongs, where are we going?" he frantically whispered from beneath his shimmering cloak.
The silvery-blue stag carried on.
"Oh, Harry," sighed Hermione sadly, when the story was revealed to her. "I'm your friend, you know, you can talk to me as well."
Harry smiled. And Prongs grew a little bit brighter, a little bit more solid, the feelings of joy grew a little bit stronger.
"Thanks, Hermione," he said quietly.
She hugged him, and it was nothing like Mrs Weasley's hug, and yet it was just as loving, just as comfortable, just as homely.
And smiling silver eyes met Harry's, seeming to say, 'I told you so'.
When Harry told Ron about Prongs, he was concerned.
"Are you sure it's ok? I've heard that lots of spells can have horrible side-effects if you get addicted to them - if you use the Cheering Charm too much, you can get depression - but I don't know anything about the Patronus Charm-"
Harry smiled. It was almost like his friends' roles were reversed.
"I don't know... but I'll ask Professor Lupin. He taught me."
"Hey, d'you think you could teach me sometime? It's so cool, and I bet the twins don't know how to cast a Patronus!"
Prongs snorted to express his disapproval of Ron, and it was like words suddenly came to Harry's mouth.
"Of course, Ron, but you don't need to learn just so you can beat your brothers. You know, it doesn't matter if you're powerful or not, or what you achieve, because you are not your brothers."
Harry didn't know where it had come from, but it didn't matter, because he meant it.
For the last time in two months, a silvery stag burst out of Harry's wand, prancing around on the grass, as if it knew it would not be called again for a while.
"Hi Prongs," said Harry.
'Hi Harry," Prongs seemed to say silently.
"I can't call you again until September, you know that? I'm sorry."
Prongs merely nuzzled his misty silver head into Harry's side, and then started to nibble on his hair.
"No Prongs!" Harry laughed. "Silly deer!"
Prongs tossed his head, affronted, as if to say, "I am no mere deer! I am much more than that!"
And not even Uncle Vernon's purple-faced rage could wipe away Harry's peace and joy.