Even the Boy Who Lived didn’t always get it right.

Despite his ‘status’, and being a rather powerful wizard as it turned out, Harry still made mistakes too. In fact, some of them turned out to be deadly.

1. Sectumsempra

When Harry picked up the seemingly innocuous second-hand Potions book, we had no idea just how important it was going to be. Although the amendments scribbled in the margins initially annoyed him, Harry soon realised their worth. These handy shortcuts transformed Harry into a Potions pro, and he was soon perusing the book whenever he got a spare minute. The Half-Blood Prince, who had written these notes, even helped to save Ron’s life when he drank poisoned mead, thanks to a hurried ‘Just shove a bezoar down their throats’ at the bottom of a page. It’s not hard to see why Harry had come to trust them – all of the additions appeared to offer helpful assistance and there hadn’t been a sniff of Dark magic, despite Hermione’s suspicions.

Harry probably thought the Sectumsempra spell, noted as ‘for enemies’, would fling the victim upside down or just send him to the floor, based on the results of previous enchantments. So when he used it on Malfoy during a confrontation, nobody was as shocked as Harry to see the ensuing bloodbath. Trying an untested spell from an unknown author wasn’t the best decision he ever made, but he definitely learned a lesson from it.