An accident causes Harry and hermione to be forever attuned to each other's thoughts and they find themselves falling for each other as their own relationships are falling apart due to it. Harry sees why she really hates fleur, she's deeply sexually attracted to the "perfect" figure. Harry's both aroused which annoys and further arouses hermione and disgusted that she would act as she did, treating her like that. Hermione is ashamed when she sees herself through Harry's thoughts.
A short time later she sees his dream of fleur and hermione seducing him for his birthday. She laughs at him then finds herself musing on it when Harry's sleeping.
A soul bond fic that's caused by a fucked up spell instead of 'true love' where the mental connection is what creates the relationship instead of the other way around.
Hermione is constantly shocked to see how Harry compares women to her and finds them lacking, save fleur, tonks, and a muggle actress (Monica Bellucci cuz DAMN!) he once met who all sit on pedestals in his mind.
She's also shocked to see he pairs fleur and tonks together in his mind/Spank Bank as an OTP.
When fleur and tonks find out about the spell and both of their attraction to the two do they want in on the relationship as well?