Hogwarts never changed.
Anyone would think that with the passage of time, Headmasters, and students, something about the stone castle would reflect the many lives that had passed through her walls. It had been something Hagrid had always wondered at when he caught a glance of Hogwarts through his window at night.
The awe that filled him with his first sight of the castle returned, no matter how often he laid eyes on the castle. The magic and knowledge in the school's depths were vast, more than anyone could discover in their lifetime, and Hagrid had never begun looking. He'd been kicked out for something he hadn't done, but had still been offered a place to stay on Hogwarts grounds.
Understandably bitter at first, he had watched his year mates continue their studies and eventually graduate. Most left Hogwarts behind, and took their jabs and fearful whispers with them. Hagrid was glad that the few that returned were the ones who had believed in him, or Hagrid was sure he would eventually had left. He didn't want to think about what would have happened to him then.
Not continuing to study was something Hagrid regretted. It had been almost fifty years that he'd had access to the library, and he'd never tried to learn more than he had been taught during his first three years. Even without overtly practicing magic, he could have spent at least some of that time learning. Dumbledore would definitely have allowed it, but the thought had simply never crossed his mind.
It always felt too late.
He hadn't been able to study until the rumours died down, or Hagrid knew that someone would have reported his supposed 'magic usage', and there would have been nothing Dumbledore could have done to prevent his stay in Azkaban. The Slytherins, especially, would have taken great pleasure in seeing him carted off to Azkaban for the second time.
Afterwards, he had been too bitter to visit the library. His desire to study was what had got him into Azkaban, or that was how it had seemed, and he hadn't wanted anything to do with it. He learned to take care of the animals under his care by trial and error. Hagrid liked to think the creatures knew he was trying, and gave him an easier time for it.
But, somewhere between hearing Filch's foul muttering and watching the Weasley Twins having so much fun with their magic, Hagrid had rekindled his desire to learn. Most of the new students, however, had begun looking up to him as an equivalent to one of their teachers. Their potential judgement had stopped him from entering the library each time.
The first time he had stepped into the library since he had been expelled was when he was looking for information to raise Norbert, his dragon hatchling. It hadn't been about him and his pride; it had been about the little dragon that was about to hatch. Despite always wanting a dragon, Hagrid didn't know how to care for one.
Hagrid had barely gotten a second glance from any of the students. Only Harry, Hermione, and Ron had questioned his presence in the library, and that was probably because they knew him and his behaviour had been suspicious. He never had learned how to behave while doing something he wasn't supposed to be doing.
A year, and one short Azkaban stay, later and Hagrid found himself innocent. He'd always known it wasn't Aragog attacking the students. He'd been contemplating borrowing a set of Third-Year textbooks from the library when Dumbledore asked him to teach Care of Magical Creatures. He hadn't been able to deny Dumbledore, the person who had convinced Dippet to allow him to stay at Hogwarts as the Groundskeeper, even if he was thoroughly underprepared and without a clue of what was supposed to be in the syllabus.
..oOo...
It was almost seventy years after he had been expelled that Hagrid was finally able to study again. Rebuilding Hogwarts had been a long process, and Hagrid had made sure to help fix every bit of the castle.
Hagrid wasn't surprised when Hogwarts didn't look exactly as it had when he first laid eyes on it. The enchantments would never be the same. Hogwarts would never have the years of magic that filled her halls before.
But it was a Hogwarts he could go back to, as an adult, to learn magic.
AN:
The Golden Snitch: [Biloko, Uagadou] Madame Malkin's Dress Up Shop– Thongs (flip flops): Write about Rubeus Hagrid
If You Dare Challenge – Time Goes By