That Soulmate au where you are color blind but you can see color on anything you're soulmate has touched would work really well for a Hogwarts couple
maybe not Perciver it would be figured out too quickly I think and take away the fun of it
honestly same for any same house ship ngl
Except Dennis/Percy i think it with Dennis/Percy would actually be very cute because when Dennis starts Hogwarts Percy will have already graduated the year before so like
Dennis knows whoever his soulmate is was in this school and was in this house but wont have a real chance of finding him until later even though he does not realise that so he still searches he still follows Percy's steps through the school which by this point are already so messy and mixed up from Percy having attended for years
The only thing is it would probably have to be something that colors overtime since if it's immediate with Percy helping with the tournament it might be too easy for them to figure out way
Like every touch to something brings the color up a bit more like leaving their magic on it so only things that have been touched heavily are in full color
Also Dennis trying to read all the books Percy had touched enough to be obvious and trying to work through a book far above his reading level because his soulmate obviously liked it