Harry Potter, the newest U13 Duelling World Champion, has lived with complete dedication to the sport and little else, barely making do with his budding apprenticeship in Alchemy(his second priority) and regular school work(barely carried over by his sheer talent and no free time), he now has to tackle the far more violent U18 circuit, his parents however deny all the world class trainers and instead hire the recently retired and two times Champion, Fleur Delacour, forced to stop competing after a cheating opponent caused the loss of her left arm and eye in the final match(which she still won).
Fleur DeLacour saw herself in Harry Potter, a natural talent and capable of extreme dedication to his goals, and like her at that age(and even now), Harry has no real friends outside his parents, his owl and his mentor Dumbledore, no time for anyone or anything else, just like she was.
And now, she had nothing, the sport she dedicated herself to for 10 years turned its back on her after her injury, her "friends" disappeared after she stopped being "DeLacour of The Silver Wand.", everyone but her family had abandoned her and this job opportunity was her last chance to keep doing what she loved, even if not in the way she wanted.
However, Fleur can't bear to see another person make the same mistakes she had, so she decides to help Harry not only be a World-Class duellist, but much more than that, to live outside the sport, to have what she hadn't, and perhaps, in trying to save him, she will save herself and find her own happiness.