(FMAB AU)

Hohenheim has a very youthful appearance and strong body with long blond hair extending to his upper back, which he keeps in a ponytail and golden eyes. The young man who would later go on to be known as Van Hohenheim grew up in the capital of the ancient and advanced country of Xerxes. As a youth, he was the twenty-third house slave of a renowned alchemist in the King of Xerxes' personal employ and was known simply as "23". Though content in his lowly position, without freedom, any knowledge of the world or even a name, the youth's life would change dramatically in his mid-teen years when his master chose him for a particular Alchemical experiment which involved taking some of the young man's blood.

While cleaning his master's laboratory one day soon afterward, 23 encountered the product of this experiment - a nearly shapeless, sentient shadowy creature kept in a flask and calling itself a Homunculus. Grateful to Slave 23 for the blood that had given it life, the Homunculus decided to give him "Van Hohenheim" as his name. But when the Homunculus realized that, as a lowly slave, Hohenheim was too ignorant to read or write, it explained that with knowledge, he would be able to escape the bonds of slavery and make something of himself in the big, wide world. As its second gift to the being it called its "father", the Homunculus began tutoring Hohenheim soon afterward, using its own mysterious knowledge to teach him reading, writing, arithmetic, science and basic alchemy. when the master discovered his remarkable skills, Hohenheim declared that, with his knowledge of alchemy, he could be a more valuable asset to the master than a mere slave and was made the master's assistant.

10 years later, Homunculus sacrificed the people of Xerxes in order to escape his glass prison as well as give his blood kin Hohenheim one last gift, eternal life and agelessness. This left Hohenheim the last survivor.

Or so he thought, you weren't in Xerxes, you returned home to find it in ruins and him alone.