The closest I've heard has been grafting a chile plant onto a tomato. I believe this was done to build tolerance to Mosaic Virus but I could be mistaken. Don't think a straight cross would work even with species within the Solanaceae family.
i would double it without some form of dna modification....but, this year in our nurseries i am seeing spicy oregano, so i picked a leaf to see why they called it "spicy oregano" and for sure, it has bite.