Tess Chambers

Backstory

Tess' relationship with her father was very toxic. She is a lot nicer and more emotional than she initially shows.
According to her father, she was always a disappointment to him, the result of a short-lived affair with a Muggle woman whose memory he wiped out so she wouldn't take Tess away from him.
Her father controlled her all her life, but that changed when he wanted to make her a Death Eater. It didn't work at first and when she was at Hogwarts all year round, Tess even felt almost free.
During this time Sofie was a big help for Tess, who started to develop feelings for the girl. It wasn't long before the two were officially a couple. She has probably never been as happy as in these 2 years.
But then Tess' father found out about Sofie and had something to pressure Tess with, as he always did.
To protect Sofie, Tess agreed to become a Death Eater and ended their relationship. But even after the break up Tess wanted to resist and tear herself away from her father which she eventually did.

She got back together with Sofie in the end.