Now, I know, flavour isn't everything.
Look. I went to the Harry Potter wiki to learn more about Neville. Dude literally got some sort of concoction involving some "evil onion" or whatever, I don't remember what it was exactly. But guess what makes me, as in Neville, feel Slytheriny? A potion that I drank prior to the game.
So maybe flavor is everything.
Neville had a big family name to live up to, and especially, brave parents. He was left an orphan and raised by his grandmother. He had such a big hole to fill, but never sized up to her grandmother's expectations. He was seen as sassy, a weakling, and he felt he did not belong in Gryffindor, where bravery is apreciated.
However, Neville was in Gryffindor because, even if he felt weak, he admired bravery greatly, and had resources deep within that were to be revealed, eventually. He did not believe in himself, his grandmother did not, many of the other students despised him, Slytherin treated him cruelly, but... some of his teachers did believe in him, some of his comrades trusted him, and, eventually, he learned to trust himself... He was trusted with lots of Harry Potter's secrets, and... there are mysterious parallels between the lives and situations of Harry and Neville, and those of his father and Peter Pettigrew (the big traitor...)
Only that Harry was less of an early assh0le an Neville grew up being standfast to the very end.
Things could have been very different, and life could have mirrored it self. It just did not.
Plus, there is more but no more spoilers are necessary.
If you want, Harry is the flashy fellow, while Neville is more a hobbit in the story, and some thrends in his life might have pushed him to doom and treason, but he proved the contrary spectacularly.
Sounds like a miller