The Stolen Child - HP x MCU

Regulus Black:The younger brother of Sirius Black, the famous Marauder. Youngest son of Orion and Walburger Black - of the Most Ancient and Nobel Black - one of the Sacred 28. When Sirius left, Regulus was expected to fulfil his role of the perfect Pureblood Wizard. He was to marry who his parent's wanted, hate Muggleborn, Half-Blood and Blood Traitor Wizards and Witches. He was destined to get the Dark Mark, and kill muggles.Regulus put on a good facade. Little did they know that Regulus was hiding a large secret that only three other people knew about.Nikita RomanoffNikita grew up in the Red Room and Hydra. The Red Room is a Russian organisation that trains young girls into becoming child assassins. Hydra is a Nazi organisation that started in WWII, where they experiment on those they kidnap, and make them into becoming ultimate weapons to destroy those they deem enemies.What happens when Regulus' family discovers his secret. What happens when people discover exactly what happened to Nikita growing up.