Six or so years ago Moonshadow appeared on the "pages" of Stories on Line and then sadly disappeared again. What a pity! He or She writes about a fundamental fantasy of a Brother and Sister, through circumstances of their own making, making love together and living together either as Husband and Wife, or simply as lovers, or more commonly as Common Law spouses; which could be spelled "Spices".
This time around Bro and Sis are twins, studying hard for their finals, and becoming more and more frustrated sexually having painted themselves into a corner by pretending to be married and living off Campus to escape the usual shenanigans of Dormitory life. Then suddenly they realize that the ideal lovers are within reach without leaving home, shall we say.
And the fuck relief turns into a wonderful night of love making, and without even having to change names they are set for the rest of their lives together.