Okay my brother came up to me today and told me what would be each sans aus type so I will be riding every Sans of you they're possible type if everything about them and all of that stuff because I think this fits for each character these are all head cannons not canon
Part 1 Dreamtale
DREAM:
Dream would love a person who's not only just as kind as he is but probably just as lonely if we know anything about dreams that he's been trapped in stone for such a long long time he probably wants someone who understands that pain of being alone he probably would understand them help them get better and the two would become close I have a feeling it would have to be someone who also loves the same things he do but would also protect him from owls because the biggest thing he fears well he would protect them from the things they fear.
This man loves every small thing you do when you cook when you clean everything you do he loves he'll even volunteer to help you knowing that you probably need some help he probably really likes the strong dominant women type though I could be wrong he probably would also love someone who's just a shy and gentle as he is probably.
His way of showing affection or cuddles and kisses and gift giving and while you two are probably alone he probably give you a nice little date for the two of you can settle down and relax.
Nightmare:
You cannot tell me Nightmare loves those type of women who probably would love everything Victorian didn't matter if you were any type whether it was more of a lighter type of Victorian or a darker though he would definitely fall over heels for someone who loves the darker he probably would also like it if you read so probably nails free time he would read.
Even if you treated like his Queen he would still be his his object his toy he'd be very very possessive of you and wouldn't let anyone around you and wouldn't let you out of his way every small thing you would do he would love he would notice it he wouldn't say anything but he would definitely notice it.
If you were manipulative and sadistic just as he was but more in the more challenged way it might be a little irritating but it might be more interesting in his opinion if you're more of the chaotic side man he'll love you so much as your chaos will probably spread across the Multiverse and make everyone struggle and heck you like roses and extra bonus.
his best way of showing affection would be gift-giving or possibly letting you just simply touch his tendrils. I'm kind of like sugar daddy he would buy you everything you like you want it a new diamond ring set a simple toy plushie a new book, hell buy it just for you.