Described by most as being friendly and very compassionate, it is never a dull moment when you're with Oliver. He is always there for anybody who ever needs someone to talk to, and most of the time he'll offer good advice. This comes from him being rather intelligent and having a way with words. Although he isn't a full on genius, he knows enough to get good grades and pass all his classes. Along with being intelligent, he is also very imaginative and can always think of different designs for certain things and writing seems to come easy to him no matter what the topic is.
Oliver can often times be rather sarcastic, in fact most of his comebacks involve some form of sarcasm. He uses it a lot in most of his jokes, and even without sarcasm he is rather funny. He loves to play practical jokes, especially on his best friends Brock and Elena. Some might describe Oliver as being cold sometimes due to some of the jokes and things he says, but that's simply his type of humour.
In a more negative aspect, Oliver has a need to always be the one who is right in an argument. Even if he's wrong, he'll keep trying to prove that he isn't and sometimes it does work, but most of the time it's just an uphill battle. It either ends in him getting mad, or the person he's trying to convince giving up. He is also sometimes oblivious to what he's saying, and it can sometimes be rather rude and he wouldn't notice. The most negative thing about his personality however is that he absolutely hates expressing his emotions. He'd rather bottle them up and end up exploding over talking them out with a friend.
After growing up in South Korea, Casey Han moved to Bow, Devon, England around the age of 24. He was born into a pure-blood family, along with a younger sister who had moved to Bow, Devon a year earlier than Casey did. She had already started a family by the time Casey had moved there, and that was his goal as well. Not long after moving, Casey met a Korean girl named Maia Seo. She herself had just moved as well, and she - unlike Casey - was a muggle. As cliche as it was, they both claimed it was love at first sight, and their wedding had only taken place a year after they met.
A month and a half after their honeymoon, Maia revealed to Casey that she was pregnant. Both of them were elated to be having a child, and when it came time Maia gave birth to a beautiful half-blood wizard whom they gave both an English name - Oliver Kohl Woojin Han - and a Korean name - Han Woo-Jin - to. From very early on, Casey and Maia could tell that Oliver would be a very very outgoing child. When he was old enough to walk, there was no keeping him in one place for more than five minutes because he'd always want to chase things or play with the darndest of things.
Oliver first magical encounter took place around the age of eight while he was colouring with Maia. After coming back from making some snacks, Maia noticed that a crayon was levitating in front of Oliver. At first she was confused, but then she remembered that she had married a wizard and that her son in return was a half-blood wizard. From that moment on, Casey started to explain the essentials of magic to Oliver. It continued until he was ten years old, and in time he turned eleven years old and was sent to Hogwarts.
During his first year at Hogwarts, Oliver was sorted into the house of ___. And not only did he get sorted, but he also met one of his best friends, Brock Kye. A year later, his other best friend Elena Baek had started her first year. The three are almost always together all the time.