@Elhao in fma manga and brotherhood, when they fight the butcher armor in the lab he scares Al with the idea that he may not have actually bein Al's soul given life in the armor, but actually a puppet-homunculus-thing that ed created to believe that it was Al as a way to overcome the grief of actually losing Al, its also disproven in a similar way where Al and winry remember a story from before he lost his body but ed didn't, so he couldn't have fabricated the memory