HP: Severus with a System

A System ran into a problem during an upgrade and transmigrated into the world of Harry Potter. It immediately found a host: an eight-year-old little girl with black hair and black eyes, living in a tiny house. She was short and skinny, with a terrible father and an even worse stepmother who only cared about herself. She was the perfect little concubine-born daughter, so the System defined itself as the Concubine's Rise System. It made plans to force the girl to study music, chess, calligraphy, painting, poetry, and literature, and to fight for favor in the household. But wait! Her father was still terrible, but the cruel stepmother who had left the girl malnourished was actually her biological aunt. The System was confused. Something about this world seemed off. This is going to be a long story, divided into three parts. Part One: The Complete Plan for a Concubine's Rise in the World. With the System's help, the little concubine-born daughter takes on her stepmother, reforms her terrible father, wins over the maids and the Hua sisters, and makes friends with her lady's companion, Evans. She meets Third Master Bu and the eldest son, encounters a strange old man and an old prisoner, and eventually opens a shop and makes her fortune. She wins back the affection of her Prince grandparents, meets a prince who carries the aura of a dragon, and rises to a comfortable life. Part Two: The Harem Upgrade System. At eleven, the little concubine-born daughter receives an invitation to the imperial selection and becomes a young lady chosen to enter the palace. She hears about Hogwarts, and the System finally understands: this isn't a household-struggle System. It's a Harem Upgrade System, and its little concubine-born daughter is going to enter the palace at eleven! The System soon finds her rival in the selection: the Potter girl, who is entering the palace in the same group, along with her relative, the Bu girl, and their senior maid, the Lu girl, and low-ranking maid, the Pei girl. There's also Empress Mai, who's been in the palace for years, and Chief Matron Pomfrey. And don't forget the big boss of the palace struggle: the Empress Dowager Albus, whom they have to defeat. Fortunately, the System's host still has allies. The all-purpose System is about to show what it can do, helping its little concubine-born daughter defeat every obstacle and win the emperor's favor. Part Three: The Empress Dowager's Path to Taming Her Husband. The struggle in the palace is long and arduous. The emperor suddenly leaves the capital and encounters danger at the border. The former little concubine-born daughter, now a mistress who has been away from the palace for years, returns to the imperial court. She must face the Empress Dowager Albus, back in power once more, the newly arrived Young Lady Ha, the imperial guard Luo, who entered the palace with her benefactor and relative, and Xiao He, a clever and capable palace maid of humble birth. How will she rise to the top once again? She still has her System. Theme: