I came up with this idea after reading too many articles about Harry's sex.
If the professor is a girl, Lily regards the professor as a good friend and best friend, but the professor falls in love with Lily. When Zhan Li's official match remains unchanged, according to the pigtail-pulling law of adolescent boys, Sirius has been bullying her because he likes the professor. Sirius accidentally discovered that the professor had an unusual feeling for Lily, so he lied that he loved James deeply and wanted to form an alliance with the professor to pursue true love together, so as to achieve his ulterior motives.
The end result was of course that the shady dog managed to knock the professor straight.
Warning: The professor has a one-way sexual orientation, the characters are definitely OOC, and there are private designs commonly used by HP fans. Main BG, slightly mentioned BL/GL. (Updates are extremely slow!! It is highly recommended to read again in two or three years!! Revise as you write.)
Vision: The path to growth in the HP pro era