Just some ideas of mine, and a few of these are REALLY fuckin fucked up and pretty sinful, so you have been warned

Like, seriously, leave before you learn how demented I am ._.

Random Senario #1 -

So, pretty much your basic love triangle Senario, though after awhile the two sanses fighting over sans A start to make their feelings a bit obvious and they eventually confess at the same time to sans A, and instead of choosing one of the two sans A decides that they should all be in a relationship together so they don't have to choose and of course there's drama, cause that's what happens in a three-way relationship

Random Senario #2 -

(Warning - this is one of the fucked up ones)
So, a sort of yandere Senario but the yandere ends up kidnapping the sans their in love with, and of course the whole kidnapping thing leads to the other sans hating them, but the yandere just decides to ignore their actual feelings and acts like they love them, and this of course leads to some fucked up sinful shit

Random Senario #3 -

Lamia Sans X a normal sans, BUT WITH A TWIST, the lamia is the sub of the relationship .w. Since I've legitimately never seen this done before, also on a side note, I need to do this Senario with errink at some point- also, another side note if the rp leads to sin at some point, fun fact lamias, since they're half snake, would have two dicks

So yeah, that's about it for now, I'll probably add onto this in the future though