The sex, as it was, was definitely hot, as you have already seen. Limits were no longer applicable; cum could fly as far as it wanted to, land anywhere inside or outside of the body, fingers and lips could roam wherever they wanted; the tongue’s taste buds were free to suckle on nipple juice or pre cum, and fingers were blessed with the sensations of rock hard penis flesh and that velvety, organic texture of a tight teenage snatch. Moans of pleasure could escalate into loud pleads for even more sex, and never was the activity stopped before each of the siblings were satisfied.
However, this, like almost everything in life, took time and luck to develop. Naturally, Bart and Lisa didn’t sporadically decide on a random chance encounter to strip each other and explore the other’s body. Innocent curiosity is always a viable starting point; especially in the tender early teenage years. Luck, perseverance over specified cultural taboos, and simply, natural attraction; these all came into play when the two blonde teens realized that the energy which they spent over the years in heated arguments and physical fights could be put to much better use, in activities that were much more physically appealing and pleasurable, though the noise obtained during their foreplay and eventual intercourse would eventually rise above any level that their petty squabbles and arguments generated.