Despite his appearance, Darche used to be human. As he began to learn alchemy form his master at the age of six, he was slowly introduced to the effects of mutagen. By itself, it caused a small minor transformation that eventually goes away. However his master wanted to create a more grand mutagen and began adding in a bit of cursed water into the mixture.
The Master, being a rather big coward, tricked Darche into taking the now poisoned mutagen. Its effects were dramatic, and slowly Darche's mind and form began to deteriorate into the creature he is now. One day after being forced a bit of even more potent mutagen Darche ended up passing out.
He dreamed while he was passed out. During his dream, he forgot who and what he was. Then he felt as though a large amount of information was being planted directly inside his brain. When he came to, his master was gone, not that Darche would remember him anyways. The master never returned after that, leaving the entire house and everything in it to Darche.
Darche didn't have any one close to him, so no one noticed his memory loss, in fact most people never even knew he was human in the first place figuring him to be some weird creation by the master alchemist.
The people of the local town didn't like the alchemist so when Darche would show up at times the made a point not to talk about the alchemist and found Darche to be quite friendly despite his strange appearance. After a while the existence of the master alchemist was forgotten entirely, while Darche took up shop as a local Apothecary.
As he grew up, he slowly came into more of an understanding of alchemy. He had figured out how to make the mutagen into something more potent without the side effects (Not that he even knew there was side effects to it anymore.)
One night in his sleep, he felt the pulse of the awakening, the name he gave to his ability to rapidly understand the creations of alchemy. It was different. It was a call telling him that the world was ending. It woke him up in what would be a cold sweat.
It was a strange feeling, he felt like he was alone, as though there was no one in this town. Indeed, anyone like him didn't exist. He knew the world was going to end, he could feel it in every fiber of himself. But he didn't know how it would or why it would.
All he knew is that if someone didn't exist that could be with him, he could create them. A lingering feeling latched on to the back of his mind, as though there was a potion of some sort he could create, but exactly how? That remained a mystery.