The parallels between Harry and Neville are interesting. but not nearly as interesting as the other person that Neville parallels and in a sense, the entire series hinges on it.
There are generational parallels as well. There essentially two stories that are being jumped between. Harry and his friend’s story, and the story of Harry’s parents and their friends. Two generations thrust into the fight against Voldemort, Harry and James, Hermonie and Lilly, Ron and Sirius. Each parallel each other and each act somewhat similar and you’d think would make similar choice if their situations were reversed. Except for one pair that couldn’t be more different…
Neville and Peter.
Both are the “tag along” friend, not in the inner circle but the main character are nice to them and protect them. Neither is particularly gifted (at first anyway) in magic, but like Dumbledore stated in the first book “It is our choices…that define who we are…”
Peter gave in, turned to the dark side, betrayed his friends, Lilly and James placed all their trust in him and he betrayed them to save himself.
When Neville was given a similar choice at the end of Deathly Hollows, being a pure blood Voldemort offers him the chance to join him, he refused, ends up the full body bind, and Voldemort decides to teach him a lesson, summons the sorting hat places it on his head and sets it on fire to signify both that there will no longer be four houses at Hogwarts, and that blood traitors will not be tolerated. However as a true Gryfindor, Neville is able to pull the Sword of Gryfindor from Sorting Hat just as Harry did in The Chamber of Secrets, and chops of Nagini’s head. (as Harry had told him to “kill the snake” if anything were to happen to him as he was heading towards the forest) The final Horcrux is destroyed, and Neville ends up as different from Peter Petigrew as Harry is from Voldemort.