Stobin as soulmates.
I don't mean the magic aus where you feel what they feel or have a shared mark or write on each other or anything.
But almost that, just in a context where that's not a real thing.
Robin has her lesbian crisis the same time Steve has his bi crisis
They always seem to catch the same disease at the same time. Robin gets her period the same day Steve gets a migraine.
They're just... connected, somehow. Intrinsically. In a way nobody else could understand.