The other members of the Bat - family, like Robin (if it's not Tim at the moment), Nightwing, etc., would also be affected. They might split up to search for him. Some might feel angry at him for leaving without a word, while others would be more understanding and worried. For example, Alfred would be very concerned and would try to keep the family together during this difficult time.
It could make Batman more determined to find him. Batman would be worried about his safety and would start an intense search. He might also feel guilty, thinking that he could have done something to prevent Tim from running away.
Tim Drake walking away in fanfiction could be a way to explore his character in a different light. It could show his independence. He might be walking away to start his own journey, to figure out who he really is outside of the shadow of the Bat - family. In some fanfictions, this could lead to him developing new skills or making new allies. It gives the writer a chance to take the character in a unique direction, away from the more traditional storylines.
One possible ending is that Tim Drake realizes he made a mistake by walking away and returns to his old life. He might come back with a new perspective and be even more effective as a hero. Another ending could be that he finds a new purpose outside of the superhero world and is content with his new life. He could be living a normal life, but still using his skills in a different way, like helping the local community in non - superhero ways.
One possible reason could be that he feels misunderstood by his family or friends. Maybe he has some secrets that he's afraid to share, and the fear of being judged makes him run away.
Spike would be heartbroken. He's like Twilight's little brother. He depends on her for guidance and love. If she runs away, he might try to find her on his own and in the process, grow up a bit as he faces challenges alone. He could also feel abandoned and struggle with his own self - worth.
For Aunt May, it would be a huge shock. She has already lost so much in her life, and Peter running away would make her feel like she has failed in some way as a guardian. She would probably be constantly looking out the window, hoping to see him come back home. Also, the villains in the story could see his absence as an opportunity. They might become more bold and start causing more chaos in the city, knowing that Spider - Man is not around to stop them.
It can also change his relationships. Maybe he becomes more distant from his friends at first because of his loneliness, but then as the story progresses, his friends notice the change and try to reach out, which then becomes a major part of the plot as they try to heal his loneliness.
His friends will surely be worried. They might start looking for him everywhere, feeling sad and confused about why he left. For his closest friends, it could be a very emotional time as they fear for his safety.
In most Tim Drake Titans fanfiction, Tim Drake is the protagonist. Alongside him, the Titans play significant roles. Starfire, for instance, might be shown as a source of support and friendship for Tim. Cyborg could be the tech - savvy teammate who helps Tim with various gadgets. Raven's mysterious nature often adds an interesting element to the stories, and Beast Boy's humor and transformation abilities are also important parts of the story.
It could cause a sense of loss. Harry is a symbol of hope for the wizarding community. His running away might make some people feel abandoned.
One idea could be a story where all of Tim's friends and family plan a surprise birthday party for him. They could transform the Batcave into a party zone with balloons and streamers. Dick Grayson could be in charge of getting Tim out of the way while everyone else sets up. They could also include a special gift like a new gadget for his detective work.