Fullmetal Alchemist: The Prototype is an early version of Fullmetal Alchemist manga chapter 1 that was drawn by Hiromu Arakawa in 2001 and published in July issue of Square Enix's Monthly Shōnen Gangan magazine in 2011 as a gift for fans to celebrate the one year anniversary of the end of the series.
For a prototype manga, both the Elric brothers' personalities are fairly consistent with their later manga counterparts, as is the story; although, in terms of transmutations, the chapter seems to show some disregard for Equivalent Exchange as Edward was able to turn a dinner knife into a sword and a few drops of tears into a sea (Though it should be noted that he had ingested a Philosopher stone prior to this). Essentially however, the chapter is just a different version of the Cornello arc; though the main antagonist, Major Arzen, shares many traits with both Cornello and Yoki.