Everyone’s already mentioned some good ones so I am going to choose some from recent BL’s that I have watched
Day 10: Best Character Development
1. Cha Si Won from Blueming. I feel he had really nice character development in this short series. He was always worried about being the perfect guy and maintaining a certain image and he had serious self-esteem issues. Alot of the issues stemmed from childhood trauma, his parents divorce, and his mom’s projections on him. I feel like Hyeong Da Un coming into his life really helped him to flourish and develop and see his true potential.
2. Sang Woo from Semantic Error started the series off as a serious but smart programming student. He was viewed as antisocial and unapproachable. He basically behaved like a machine would. With Jae Young coming into his life, he was able to loosen up, enjoy life more, and smile more. He became more friendly by the end and willing to accept friends and etc. into his life.
So, I feel like these two characters development for the better was greatly helped/triggered by their romantic partners coming into their lives.