There might be a mysterious character who only appears at the end of the road and has some special powers or knowledge. This kind of character tends to be quite memorable because they add an element of mystery and intrigue. Also, characters with a great sense of humor can be memorable, even in a somewhat serious story like 'at the end of the road manhwa fanfic', as they can lighten the mood and make the story more engaging.
Arya Stark is another favorite. Her skills as an assassin and her desire for revenge can be further explored in fanfic. For example, in a manhwa fanfic, she could have adventures in new lands while still on her path of vengeance.