Well, I'm not sure about specific 'Daphne saves Harry from the Dursleys' fanfiction titles off the top of my head. But you could also try Fanfiction.net. Browse through the Harry Potter section and look for tags related to Daphne and Harry's rescue from the Dursleys. It might take a bit of time, but you're likely to find some great reads there.
Daphne could be a fictional character created specifically for this fanfic. She might be a witch from a well - known wizarding family. Maybe she's a classmate of Harry's at Hogwarts or someone who has just heard about his situation and feels compelled to help.
It could be that Daphne has a personal connection to Harry that she's not aware of until she starts investigating the strange magical disturbances around the Dursleys' place. Once she realizes it's Harry in trouble, she enlists the help of her friends or some sympathetic wizards to break Harry free. She might also face some challenges along the way, like dealing with the Dursleys' resistance or the Ministry of Magic's rules about interfering in Muggle affairs.
Well, perhaps Daphne somehow discovers Harry's awful situation at the Dursleys. She might use magic to break into the house secretly. Then she could use a spell to make the Dursleys forget about Harry so that she can take him away without a fuss.
In this fanfiction scenario, Bellatrix saving Harry from the Dursleys is quite an unexpected twist. It could be that Bellatrix has some ulterior motive. Maybe she wants to use Harry for her own dark purposes against Voldemort. She might see Harry as a valuable pawn in the power struggle within the Death Eater ranks.
The Dursleys might be left in a state of shock and confusion. Since they have been so mean to Harry, they could be worried that the wizarding world will come after them for revenge. But since they are Muggles, the wizarding world may just leave them be, but they will always live in fear of the unknown.
One popular 'daphne saves harry fanfic' might be found on Fanfiction.net. You can search there using those keywords to discover stories where Daphne plays a crucial role in saving Harry.
Perhaps Snape uses magic to create a distraction at the Dursleys' place. He could make strange noises or apparitions that scare the Dursleys, and while they are in a panic, he grabs Harry and disapparates. This would be a quick and efficient way for him to rescue Harry.
Maybe Percy uses his magic skills to create a distraction. He could conjure up some strange creatures outside the Dursleys' house. The Dursleys, being afraid of all things magical, would be distracted long enough for Percy to sneak in and get Harry out.
Well, Daphne in the 'Daphne meets the Dursleys fanfiction' would probably interact with the Dursleys in a very cautious way at the start. She would be observing their behavior towards Harry closely. Once she realizes the extent of their nastiness, she could try different approaches. She might try to reason with them, explaining how wrong it is to treat a child like that. When that doesn't work, she could use her magical abilities to disrupt their daily routine in a harmless but annoying way, like making the TV constantly change channels or the kettle never boil. This would be her way of getting back at them for their treatment of Harry and also a way to show them that there are forces they don't understand.
One possible plot could be that Voldemort realizes Harry's importance in a different way. Maybe he sees that Harry has some power or knowledge that could be useful to him in the long run. So, instead of wanting to kill Harry, he decides to rescue him from the Dursleys to gain his trust and manipulate him later. For example, Voldemort might think that Harry has a connection to some ancient magic that only he can access, and by saving him, he hopes to get access to it through Harry.