Describe, in detail, a character's room. Leave no wall, no closet, no colours unexplored. Let the details flow from your mind's eye, suggest character traits with the things that occupy their room, craft a vivid scene.
What music your character listens to, what books they read, what they keep as trinkets or prized possessions, can reveal your character to be as real your neighbour next door. Make readers intrigued by your character, their oddities and quirks.
You can do this for your favourite character, or better yet, help us love a character that has yet to exist.