Ok so this plot is rather simple and also Adaptable for MxM FxF or MxF
all it really starts off is with a simple action while one twin is sleeping the other (Having always had an attraction to their twin) starts to mess with them. slowly at first maybe stroking through clothes or kissing necks but night after night he/she keeps coming back and getting a little riskier wondering just what they can get away with. Does the victim find out? Does the victim already know and secretly like it? Has the victim done the same thing to the other twin?
as I said completely adaptable
I am also flexible on which Role I play
PM if interested and we can discuss plot ideas