One possible plot could be that Gabrielle gets into some serious danger in the wizarding world, perhaps during a new dark wizard uprising. Harry Potter saves her life, and thus Gabrielle owes him a life debt. Gabrielle, being a proud and determined character, insists on following Harry around to repay the debt. This could lead to various adventures where she uses her Beauxbatons skills to assist Harry in his quests, like fighting off dark creatures or uncovering secrets in the wizarding world.
Maybe Gabrielle witnesses Harry being wrongly accused of a crime in the wizarding world. She steps forward and uses her testimony to clear his name, which in a way incurs a life - debt - like situation as Harry's life was on the line. As a result, Harry, feeling indebted to her for standing up for him, takes her under his wing. They then go on a journey to find the real culprit together, facing many challenges along the way, like dealing with magical traps and false leads.
She could save Harry's life in a really dramatic way. For example, if Harry was about to be attacked by a powerful dark wizard, Gabrielle could use some unique Beauxbatons magic she has learned to shield Harry and then defeat the attacker. This would be a clear way of repaying the life debt as she has literally saved his life in return.
A really interesting plot could be that the life debt is not just about saving Gabrielle's physical life, but also her magical essence. Harry then has to take her on a journey through different magical realms to restore her magic, all while facing various challenges and making new allies along the way.
In some fanfiction, Gabrielle might be the target of a dark curse. The story could be about how the characters in Harry Potter's world try to find a way to break the curse. It could involve a lot of research into dark magic and ancient spells.
One possible plot is that Harry calls in the life debt to gain an ally in a dangerous magical tournament. In the lemon fanfiction, this new ally, bound by the life debt, becomes very close to Harry. They start to have feelings for each other, and there are some sensual scenes between them during their training for the tournament. The story could then revolve around their relationship development while also showing how the life debt affects the events of the tournament.
Perhaps they fall in love. Gabrielle, having grown up and seen Harry's heroics in the war, might develop a deep admiration for him that turns into love. Harry, on the other hand, is drawn to Gabrielle's courage and her different perspective on magic, being from a different magical culture. They would face challenges though, like dealing with the post - war prejudices and the rebuilding of the wizarding world while trying to build their relationship.
Well, perhaps in the fanfiction, Gabrielle Delacour is in a cooking class at Beauxbatons. They are learning to make a special magical dish that requires a lemon. But this lemon is no ordinary lemon. When Gabrielle starts to use it in the recipe, it starts to glow and create a portal. Through this portal, she enters a parallel wizarding world where the rules of magic are slightly different. There, she has to find a way to get back home while also dealing with the challenges of this new world, all with the lemon as her starting point.
One possible plot could be that after the war, Harry Potter travels to France for some reason, perhaps for international magical cooperation. There he meets Gabrielle Delacour again. They start to bond over their shared experiences of the Tri - wizard Tournament and the fight against the Dark Lord. Gabrielle has grown into a confident and intelligent witch. As they spend more time together, they realize their feelings for each other and eventually get married. Their marriage could also bring the wizarding communities of Britain and France closer together.
It can introduce new plot twists. For example, a character who was thought to be an antagonist might turn out to be an ally because of a life debt to one of the main characters.
In this fanfiction, it's likely that Harry and Gabrielle will interact with some of the Weasley family members. Since Gabrielle is Fleur's sister, the Weasleys could play a role in how the life debt is dealt with. They might offer advice or resources. And of course, they could also be involved in any conflicts that arise. Also, there could be interactions with some of the Hogwarts professors, who might have their own insights on life debts and how to handle them in the wizarding world.
Well, perhaps in this fanfiction, Gabrielle has grown up and is now a strong and independent witch. Harry, still dealing with his fame, finds solace in Gabrielle's genuine nature. They meet at a magical event in France. Their relationship begins with a simple dance and then blossoms as they exchange letters through owls. As they fall deeper in love, they face some opposition from those who think their relationship is too sudden. But they overcome it and get married in a beautiful ceremony by the Black Lake at Hogwarts.