I'm not sure how good this is, and its probably a bit jumbled, but I kind of like it.
This is the fault of the picture of Matthew Lewis floating around tumblr in a tan tweed jacket with sunglasses and tags that gave me the idea for this fic
disclaimer: if you dont know who owns harry potter, I dont know what to tell you
Neville didn't really mean, or expect, to become the 'cool' professor. He supposed that he had become well known for fighting with Harry against Voldemort, and lord knows killing Nagini had certainly helped, but he had also, over the years, collected rather a selection of oddities, in manner and physical possessions.
After the battle of Hogwarts, Neville had summoned his courage and persuaded Professor McGonagall to let him take his exams as early as possibly(the battle had made him stubborn, and so he stubbornly passed them). She had, with a healthy dose of surprise, allowed it, and once he had confessed his plan of travelling the world, both magical and muggle, arranged for him to study under a friend of hers, Rufus Holdsworth. Neville had collected his belongings and travelled to just outside to the school's warding, where he promptly apparated to Bulgaria to meet his new teacher.
Rufus Holdsworth was eccentric, there was no other word for it. He was both far younger than Neville had assumed, and loonier than a box of bogtrolls. He was a tall, muscular African man, with pink hair(though Neville soon discovered he changed it on a whim every few weeks) and a deep, resonating voice not unlike that of Kingsley Shacklebolt. When Neville had arrived, Rufus had hauled him into a fairy ring. Once he had bargained with the pixie in residence for her crop of pigwitherins, they had returned, and then Rufus directed him to the house they were staying in, a small cottage in a field, surrounded by cows, and completely isolated from both magical and muggle society.
The next morning, he had been woken and ordered to wear muggle clothes.
"Are we going into a village?"He had asked.
"No." Rufus had poked him and then left, and upon leaving the cottage, Neville had found out it was far easier to crawl around in mud wearing jeans than robes. Rufus had made him till flowerbeds of snapdragons for weeks, made him care for them until he had learned to evade the bites of the toothy plants, and also how to tend to them properly. Then Neville spent a week caring for the cows.
And so it continued, a trend developing in the alternation between muggle and magical education. Six months in, they travelled to meet with Charlie Weasley, and Neville spent eight months working with baby dragons, abandoned by their mother, and studying the plant life and how it was affected by dragon dung. He acquired a dragon hide jacket, which Rufus declared made him look rakish, and gave him a dragon fang, threaded onto a leather cord. Then they travelled to America, where Neville gained his degree in herbology. It took him three years, under Rufus's tutelage, and they then flew(on a muggle plane, and Neville has never been so ill while travelling in his life as he was while flying in that tin can) to Russia, where they lived for a year and studied the ice mermaids there, and the algae they lived on. Neville learned mermish and Russian simultaneously, since they were all Rufus spoke whilst there.
On his twenty third birthday, Neville almost died. A stray chimera had been roaming a French forest, and had clawed a huge gash into his ribs. Neville had been too distracted by what he was fairly sure was a new species of mushroom with the properties of bone regrowth and levitation when it had attacked, and he had barely survived, only doing so because Rufus had grown impatient and set out to search for him. He had made a fairly fast recovery, even though he scarred heavily, but was much more wary from then on, with good reason, because the following month he was nearly bitten by a gorgon in a Nigerian cave.
Nine years with Rufus had made Neville one of the leading herbology experts in the world, and his thesis on floating cacti in the little known Slovenian desert had turned out job offers globally. He had accepted a position at Hogwarts, as the herbology professor, and was extremely pleased to discover that McGonagall had assumed the position of headmistress.
At twenty seven years old, Neville Longbottom became the herbology professor at Hogwarts school of witchcraft and wizardry. He was renowned for wearing muggle clothes as much as possible, claiming frequently it was easier to garden in, and proved it when he caught an escaping hopperbulb, diving headlong to retrieve it before it knocked a student down. He wore odd pieces of jewellery, the most prominent of which was a dragon tooth necklace, and an albanian voodoo bracelet. Beaded bracelets adorned his arms, and various magical and non magical rings sat on constantly muddy fingers. He constantly had a pair of sunglasses, whether they were perched on his nose, pushed up onto his head, or tucked in the front of his tshirt, and he wore muggle cardigans excessively.
Every summer he vanished from Hogwarts, coming back with all sorts of trinkets, from magical markets worldwide, and his office was cluttered and stacked with plants, skulls and paintings. Frequent visitors met with him in there, and sometimes crashing and explosions would echo down the corridor. Most notably, one December, a short blonde woman had visited, and had evidently brought along an exploding carva plant, which emitted bursts of fire every few minutes. Neville had emerged with a permanently singed eyebrow.
Students came to him for advice, tea, or study sessions. He was often found in the forbidden forest, studying the plants there, as they didn't grow anywhere else. And he usually wandered the castle deep in thought, muttering in different languages, his own Scottish accent still prevalent.
So Neville hadn't really expected to be a cool professor. But he couldn't say he didn't know why it had happened.