I couldn't find any details on Dante and Hohenheim's son except he apparently died of mercury poisoning age 18. I couldn't find a name so I've called him Lucas. If any one knows any more canon details feel free to contact me.

I have now changed his name to William which is apparently cannon.

He only knew darkness. He knew nothing of anything all he had ever known was the darkness of the void and a name. Envy.

The there was a blinding white light, closing his eyes he headed towards it curious. He was in a white space with nothing but a gate and a figure who called himself truth. There was also a man standing at that gate. A tall blonde man with golden eyes. Hohenheim of light.

His next memory was of waking in pain in the middle of a circle. The man from the gate and woman kneeling over him. The woman had wept and memory's came flooding back. memory's that he knew weren't his.

The woman was called Dante, he recongnised her as "mother" she had smiled but when he had turned and acknowledged "father" he had been more hesitant. But he had smiled and embraced him. But he had felt no affection for either of them.

They called him "William" and treated him as their son. But he was not this William there was difference that although subtle at first became clearer to his "parents".

He wasn't William Von Hohenheim he was Envy, and when he was addressed as "William" it always seemed wrong.

He was his own person with a distinct personality who bore the face of a now long dead young man.

William von Hohenheim had been a young man who smiled easily, while Envy also smiled easily his were twisted smirks whereas William's had been open smiles. Willaim's temperament had been very alike his youngest half brother Alphonse who he would never have met even if he had lived to a ripe old age he would have died long before the birth of his half brothers.

Lucas had been a gifted alchemist, hungry for knowledge. Just as Edward was but Envy cared little for anything that didn't benefit or amuse him.

Althougth Dante and Hohenheim both called him "William" there was a certain amount of disappointment in their eyes when they scanned his features as if seeking to reassure themselves they had brought back their son.

He found almost by accident that he could change shape easily and delighted in tormenting the village children by becoming some sort of monster. He had laughed it was a cruel laugh not like the man he was supposed to be. Dante had turned away tears in her eyes but Hohenheim had confronted him. Envy had just smirked and Hohenheim had stared into his eyes and then recoiled in horror, "you're not William, you're not my son." He had whispered Dante and Envy never saw him again.

Envy had been furious they had called him into this world. This world he could not appreciate, he found it hard to feel things, he had no soul and this was Hohenheim's fault how dare he abandon him.

But Hohenheim had been right he was not William he was Envy. The name he had always known, it had felt so wrong when they called him William but at the same time he had wanted to be William, so badly that was why he had tolerated it for so long. But he couldn't pretend to be human, he didn't know what it was like to have a soul. He could fake compassion for a while but he couldn't fake having a soul.

So he changed his physical self to suit his personality. Purple eyes and green hair, green the colour of Envy. A muscular lithe almost androgynous form. It suited him and while Dante stopped expecting him to be William she stopped treating him as her son started to call him by his true name he became her lieutenant but he would never be her son again.

No he reminds himself he never was her, he hates the fact he has these memories of feelings that he cannot experience himself.

He is jealous of the now long dead Willian Van Hohenheim and he is jealous of the humans who can experience feelings. Jealous of everything and everyone.

What little is left of William van Hohenheim in his memories screams at him when he is cruel to Dante,when he kills, when he laughs. Envy ignores him.