Lena was born in Arnis, Germany (known mostly for being the smallest town in Germany), a few years after her older sister Monika. Her father left her, her mother and her sister when she was three, but not soon after her mother started dating a woman she'd once met in Berlin. The family were rather happy in Arnis, despite the odd looks they would sometimes get.
Her young life wasn't very easy due to having two mothers by now and scaring quite a lot of the local children. She wasn't very fond of anyone other than her two parents and elder sister. When both sisters started showing signs of magic, their mother Odette explained to their step-mother that she herself was a witch and so were the kids. They decided to move to England so their kids could attend Hogwarts rather than Durmstrang.
Monika had been sorted into Huffelpuff, so when it was time for Lena to start school she hoped that's where she would be put. Whilst waiting for her sister to hurry up and get both their trunks and bags, she noticed a girl had hurt herself whilst running into a wall. Deciding to help her, she introduced herself and took her to the teacher's carriage. The girl she'd met was a third year Gryffindor called Isabelle and surprisingly the two got on rather well.
Although Slytherin would have been a much better choice for Lena, she was placed into Hufflepuff as she wished. But as she got older she stopped paying much attention to Monika and focused more on Isabelle. When Isabelle graduted she was rather sad, but she still got quite a lot of help on her exams from her friend. When she herself finally left school she moved into Isabelle's home in Diagon Alley.
Deeply in love with Isabelle since they met, Lena was distraught at the sights of seeing her with another person romantically. She left for a few months, mostly wondering around the countryside of Germany until after Isabelle was married and had children. She confessed her love, which was returned but made Isabelle forget everything - a kiss included. For now, she stays in London but is unsure how long it will be until she goes missing again.