Flame Valkyrie

The overused reader ends up in KHR, the fun part might be the fact I never watched the episodes, all my knowledge is based on other writer's stories.
Summary, the reader is twins with Tsunayoshi, they saw what Nono and their father seal Tsuna and realized that their family isn't going to protect them. They tried to convince Tsuna to leave with them, but due to the seal on his Flames, Tsuna did not leave with the reader. The reader leaves and uses their past knowledge to their advantage to succeed in life and protect themselves from Vongolia taking them back. Years later, the reader has mastered their flames and returned to their hometown to remove the seal on Tsuna's flames, only to land straight into the Ring Battle arc. We will move forward from there.
*Side note: The reader only knows as much as their writer, I will of course change the source of their knowledge, but just telling you so your all aware. Enjoy.*