To your first question: Yes. The most obvious way, of course, would be something like telepathy or hypnosis. I was [i] also [/i] thinking that a sorcerer could, say, correct the incantation used to bring Anguish back and to fix his current...issue. The broken spell was what caused Anguish to lose all of his memories and his personality from his previous life. 

To answer your second question, he only grows when he absorbs fire and such things. I was a bit apprehensive of putting a solid rate of growth in, because I wasn't sure what would be considered too overpowered. To double his size, though? I'd say...Perhaps absorbing a pile of ash about the size of a two story building. Strength wise, I wasn't sure which was a better course. I'd like to say exponentially, but again, I didn't want him to be able to go toe to toe with someone like Zenith too early on in his existence.

Really? I was worried I had skimped out on too many of the details. It's nice to know it wasn't as bad as I perceived.