Elissa was born to muggle Italian father Matteo Bastianich and a half-veela French mother Solenn Brochant in sunny Florence, Italy. She is the eldest of three siblings, and the only girl. She had an okay childhood, well enough for a middle-class family in Europe. Her father was well aware of the wizarding world, and so she grew up immersed in the culture of magic. Before she turned eleven, she was sent to muggle school though, and her mother was slightly afraid she hadn't inherited her magic because she hasn't shown any signs of being able to wield it. She was proven wrong though, when Elissa managed to shortcircuit all electrical devices in their home in a fit of rage directed towards her younger brothers at age ten. She soon received her admission letter from Beauxbatons after that and her mother was more than happy to send her first magical child to school.
At Beauxbatons, Elissa learned how to become a responsible, capable, driven and ambitious young woman. She had aced almost all her classes, and was doing well in the social aspect, too. She played Quidditch, even became captain, was a prefect and was also appointed as Head Girl in her final year. It was also during that time that she discovered her bisexuality, accepted it and embraced it. She started dating one of the girls in her batch, a Korean girl named Helen, and they went on to travel the world after graduation. She came out to her family after that summer, and she had tears in her eyes when her father and mother hugged her and told her they couldn't be more proud of her. After that period of bliss, Elissa eventually started looking for a job.
It was no secret that Elissa's best class had always been Defense Against the Dark Arts, and she just had this natural skill in dueling. Her fighting style has been described as "graceful, but deadly," by her peers and it was also no secret that she wanted to become an auror ever since she was a little girl. And so she applied to become part of the French Ministry's Auror force, together with her then girlfriend, Helen. They both rose the ranks together, became more proficient with their crafts, and eventually fell deeper in love. After five years of being together, Helen proposed marriage to Elissa, who gladly said yes. They became engaged at age of twenty-three, and everyone was happy for them. They were the rising power couple, and LGBTQ+ too, and they were well-known among their peers and the other people in the French Ministry.
Not stories end well, though, and Elissa and Helen are no exception. A year after their engagement and roughly four months before their wedding, both were recruited into a special mission to capture high-profile wizarding criminals in China. They were both ground agents, or basically the soldiers during the operation who engaged into direct combat with the criminals. Things turned dark and Helen was murdered in battle, right in front of Elissa. She quickly avenged her fiancée and killed both of their opponents, but needless to say, she was devastated.
Elissa left the auror force shortly after that, and disappeared from everyone - the only person who knew where she went to was her youngest brother, Raphaël, who refused to tell anyone of her whereabouts, keeping his promise to his sister. Elissa fled to a small island off the coast of mainland Greece, and lived among the muggles. She grieved and was depressed for about two years, before she eventually found peace and enlightenment. It was very hard and distressing for her, but she knew that Helen would want her to let go and move on. And so she did.
Moving back to Italy, Elissa decided to do away with being an Auror completely. She decided to sign up for a teaching job instead, an arguably less violent career than her previous one. She was accepted to teach Defense Against the Dark Arts, her best subject, at Beauxbatons, her alma mater. She became a well-known professor among the students, who was strict but very effective, and was generally liked, although feared of by some. After four years of teaching, the then Headmistress of Beauxbatons stepped down, and she was elected as the replacement at just a young age of twenty-nine for her talents and intellect. Right now, she is leading her school to Hogwarts to participate in the Triwizard Tournament, and she is determined to take the victory.