If Harry Potter trains in the Time Chamber in fanfiction, he might discover new magical abilities that he didn't know he had. The Time Chamber is a place full of possibilities. He could use the extra time to study the history of magic more deeply, which could give him insights into how to defeat his enemies. He could also train his physical strength and endurance, which are often overlooked in magic training. This would make him a more well - rounded wizard, better equipped to face the challenges ahead.
In a time chamber in Harry Potter fanfiction, perhaps students could go back in time to witness key events in wizarding history. For example, they might see the founding of Hogwarts, which could be a really exciting adventure. They could meet the four founders and learn about their intentions and the magic they used to build the school.
In this fanfiction, the goblins could enter the time chamber to change some past events related to their relationship with wizards. Maybe they want to rewrite the history of how they were treated or how certain magical items were distributed. The time chamber gives them the opportunity to manipulate time and make things different for their kind. They could also encounter various magical creatures from different time periods inside the chamber, leading to all sorts of adventures and challenges.
It could be about Harry finding a secret training ground in the Chamber of Secrets. Maybe he discovers ancient spells or magical creatures there that help him train for upcoming battles against Voldemort.
Sirius Black could be a trainer. Sirius, being Harry's godfather, would be highly motivated to train Harry. He could use the time - turner to go back to a time when he was at his peak in terms of combat skills and pass on his knowledge to Harry, especially in the areas of dark - wizard fighting and survival skills.
It could be Dumbledore. He always seems to know about the hidden places and secrets in Hogwarts. He might secretly guide Harry to the Chamber of Secrets for training and provide him with some cryptic advice.
His relationships with his friends could become stronger. Since he's training in the Time Chamber, he might come out more confident and skilled. His friends would look up to him more. For example, Ron might be even more in awe of him, and Hermione would be proud of his progress.
An old train conductor who has been working on the Hogwarts Express for decades. He has seen many strange things over the years and has some knowledge about the Chamber of Secrets that he has kept to himself. Maybe he was once involved in an incident related to the Chamber and now he is a key figure in helping the students solve the new mystery.
Maybe Harry could meet new friends while training. He might discover new magical abilities related to his training. Or he could face some challenges that test his limits.
One idea could be a story where the Hogwarts Express itself is enchanted to lead students to a hidden entrance of the Chamber of Secrets. Maybe the train tracks shift and take the students on a wild ride to a secret location near the Chamber.
In the fanfiction, they could face a common enemy. Naruto, with his powerful ninjutsu and Shikamaru, with his clever strategies, would have to work together. For example, they might be up against a group of rogue ninjas. Naruto could be the main force in direct combat, while Shikamaru uses his shadow jutsu to immobilize the enemies at crucial moments, and during their training, they prepare for such scenarios.