Due to her heritage, Fleur has grown up with a lingering paranoia that borders on generational trauma. Veela are, and always will be, perceived a "certain way," that makes her skin crawl and keeps her up at night sometimes. Then the Triwizard Tournament was announced, and she saw it as a way to prove to herself that she wasn't, and never would be, a victim.
And then she came last in the first task.
And then she spent the entirety of the Yule Ball struggling to ignore the countless eyes running up and down her body.
And then she was dragged under the lake by Gringlylows, their tiny claws popping her bubblehead charm and stealing her breath away, and when she finally made it back to the surface she had a bone chilling realization.
They had taken her wand.
Headmaster Dumbledore had summoned it with a flick of his own wand less than five minutes after she realized it was missing and she had been safely reunited with it, but the chill that ran down her spine at the realization that she was completely helpless without that slim stick of wood was enough to interfere with her sleep for days.
And then, when walking down a corridor, she heard something that made her heart leap into her throat.
Harry Potter, her fellow champion and the one who had rescued her sister from the lake when she couldn't, talking to his friends about dodging punches and outrunning someone named Piers Polkiss.
She began eavesdropping immediately.
She learned many things about Harry Potter then that she would never have guessed.
She learned that he had been raised by muggles, that they were not kind to him and that he had needed to find other ways to survive, and that he had done it all without magic.
Fleur is paranoid about losing her wand and overhears Harry talking about learning to fight back against Dudley's boxing the muggle way, then asks him to train her to defend herself without magic in case she ever loses her wand again.
Ron and Hermione get involved too. Hermione by researching muggle self defense theory so that they have a clue what they're doing, Ron by applying his athletics fanaticism to Harry and Fleur’s training.