Neville Longbottom could not cast a Patronus when he first tried in his fifth year even with Harry's help. He figured he didn't have a happy enough memory for it which he really didn't. He felt left out since all his friends could cast a Patronus. He really wanted to be able to cast a Patronus.

It was now about a month after The Battle of Hogwarts. He decided to try again. He tried using the same memory that he had used before again it did not work. He tried again but it was only a wisp. He needed a stronger memory.

It was another month and he tried again but no dice. He tried again and got another wisp. He continued trying over the next few months but again he did not get it..

He finally achieved it in November of that year. His Patronus was in the form of a teddy bear. He grinned at it. He thought it fit him perfectly.

The memory was of his gran telling him that she was finally proud of him. This made him happy. The first person he told besides his gran was his mum and dad despite not being able to understand him they were proud just as they're were when he fought in the battle.

He told everyone about it so they knew it was his Patronus and it wouldn't be surprising. They were so happy for him. His gran told him that his father's Patronus was also a bear. He was proud to have the same Patronus as his dad. He felt closer to his dad. He had got a few comparisons to his mum but it's nice to have to his dad.

He named his Patronus Winnie which he found out was a fictional muggle bear from Hermione. It fit him perfectly. He grew very close to it.