After Voldemort returned during the 3rd task, Dumbledore is not the only one who decided to act. Nor is he the only one who has a bird as club mascot. After all, due to Crouch Jr's plotting, Fleur was tortured with the Cruciatus, and her mother decides that whatever the British get up to is their problem, but her daughter was one bridge too far. So she gets in touch with her own mother, and her covern.
Fleur is quite annoyed, she had been looking forwards to spending her summer in London to work on her English before her job starts. Instead, her mother dragged her off to Burgundy to meet all kinds of distant relatives, including a rather stuck-up Duchess. They ask her all sorts of questions about the Tournament, the Third Task, Harry and Cedric. Her ducal aunt also decides to force some political lessons on her where they analyse how the British ministry is "handling" the situation. She also sends off a few people to keep an eye on Harry. The Order guard suspects that someone is watching Harry, they however conclude that Voldemort is behind it.
Fast forward to the dementor attack, Mundungus might be off doing shady deals, but the Covern guard is there. Before Harry can do anything about the dementors, the guard drives them off. Harry is quite surprised when his mysterious saviour turns out to be an attractive French blonde - he asks a bunch of questions, long enough for the Ministry letter that expels him to arrive. Harry panics, the Veela guard tells him that she will take care of it. One apparation later, before the Order can do as much as contact him, Harry is in France and retelling what has happened.
The Duchess is rather annoyed, he had saved her distant niece and now his Ministry was trying to assassinate him, so she decides to have a go at the Ministry. After all, they attacked an envoy with Diplomatic accreditation who was just out on a nightly stroll. Near to where Harry Potter lives? It was a nice neighbourhood - basically a Diplomatic shitstorm for Fudge while Dumbledore isn't left looking much better since Harry Potter has disappeared.
Harry meanwhile meets Fleur, and they bond over being stuck at a Veela covern. Harry is quite surprised that anyone cares, Dumbledore had ordered him practically isolated after all, and all those lessons are great bonding time. Nothing like a good duel to get the heart pumping after all. Fleur has to translate often since not all in the covern speak English. They promise to keep an eye on him as they plot their own actions against Voldemort, his attack on Fleur had awoken their own ire
So when Harry returns to Hogwarts, he is not only a subject of the Duchess of Burgundy, but also got Diplomatic immunity (International Magical Cooperation is a mess after Crouch and the paperwork was filed correctly). This greatly annoys Umbridge, who cannot go ahead with her plans. Meanwhile Harry stays in touch with Fleur, and the combination of her being able to apparate to Hogsmeade and Harry having the Marauder Map and his Cloak open up a lot of possibilities to meet in the evenings. Fleur has not yet met a lot of people at work, so Harry is a welcome dinner partner... And one thing leads to another...
Bonus points if Harry sends a letter to the order telling him that he is alright, but the letter is written in French and no one there can speak French so they think it's some obscure code. Only Hermione can do a rudimentary translation, but she keeps quiet about it before sending her own reply where she explains the whole situation with Dumbledore’s orders and whatnot. Harry is annoyed, but not at her or Ron. This is not supposed to be a trio bashing after all.