Fullmetal Alchemist: Brotherhood largely focuses on the Elric brothers and their quest to atone for their crime of human transmutation. But the series soon makes it clear that alchemy runs in their family. The brothers lost their beloved mother Trisha Elric years ago, and they weren't the only ones to mourn her. Their dad, Van Hohenheim, always regreted losing his wife, which was only the latest loss of many.
Van Hohenheim first appeared in Fullmetal Alchemist as Ed and Al's estranged father, a well-dressed bearded man with a blond ponytail to match Ed's and alchemy skills, which were unlike anything the world has ever seen. His life story is a bizarre one, even in a world of deadly homunculi and talking human-animal hybrids.
Hohenheim's Origin as Slave #23, Cultivated As Father's Minion
A few centuries ago, the desert between Amestris and the great land of Xing was home to a powerful city-state known as Xerxes, a nation that supported slavery. One particular slave was a blond, young man known only as slave #23, and he thought that this would be his entire life. But he was wrong. One fateful afternoon, slave #23 was cleaning up an alchemy lab when a voice called out to him. A tiny dark creature in a glass flask introduced itself as the "dwarf in the flask." This little critter dreamed of greatness and invited slave #23 to come along for the ride. To make slave #23 a worthy minion, the dwarf named him "Van Hohenheim," a name it dreamed up out of thin air. Hohenheim and his tiny friend soon became master and apprentice.
Hohenheim won his freedom and spent years studying alchemy, symbology and other arcane arts from many respected teachers across Xerxes. In particular, the Xerxian king dreamed of immortality, and Hohenheim and his little friend promised to give it to him. They had the king's men dig a huge transmutation circle across all of Xerxes, passing it off as a series of irrigation canals. Hohenheim and the king were totally deceived, however. The alchemy ritual didn't grant the king immortality, but rather, it absorbed all one million souls in Xerxes and condensed them into a Philosopher's Stone. The dwarf received half and granted Hohenheim the other half out of gratitude.
Hohenheim awoke as a supernatural but lonely being -- the last surviving Xerxian of all. The dwarf, which had obtained Father's DNA from a blood sample, assumed his likeness to prepare for the next phase of its grand plan. The dwarf, which now looked like and spoke like Hohenheim, would later become the villain Father, and shape the entire nation of Amestris around his grand plan. Luckily, Hohenheim was there to stop him.
Van Hohenheim: The Golden Sage, The Father, The Monster, The Hero
For many years after that incident, the now-immortal Hohenheim wandered the world, spreading the secrets of alchemy and alkahestry to anyone who would listen. The people of Xing used his lessons to perfect their alkahestry arts, while the Amestrians started using alchemy. Hohenheim, as a living Philosopher's Stone, had access to the 500,000-odd souls inside him, and he spoke with all of them to maintain the spirit of Xerxes. He also wandered Amestris in a great circle, implanting souls here and there to lay the groundwork for his counterattack against Father, as well as befriended and lost many human friends. Finally, he married a certain Trisha Elric and had two sons with her. Hohenheim was reduced to tears when Trisha sternly told him that he was not a monster, but rather a wonderful person, and he should find happiness in that.
Hohenheim was rarely there for his family, though, which fostered deep resentment in the oldest son, Edward (especially when Trisha died). Hohenheim was continuing to lay the groundwork for his revenge against Father, and he even found his way into the huge, circular tunnel that contained the shadowy Pride. Hohenheim was also one of Father's five sacrifices to open the portal of truth since he was a living Philosopher's Stone and had seen the Truth. Sure enough, on the Promised Day, Hohenheim ferociously fought Father with all his might, trusting his son Edward would finish the job, which he did. Father was beaten and Hohenheim's long struggle against his evil twin was over at last.
Hohenheim had nothing left to do in the mortal realm of Fullmetal Alchemist, so he visited Trisha's grave one last time where he was relieved to finally have a chance to join her. Pinako Rockbell watched the bittersweet scene unfold as Hohenheim allowed himself to crumble away and perish to reunite with his wife. He lived a supernaturally long life of hardship, wandering and scheming. Poor slave #23 never asked for any of this. But when he finally reached the end of his arduous trek, he died happy -- and that's what matters most.