Found: Series where some people are bonded to Dragon souls?

I can't for the life of me remember the name of the series or even the characters, but I do know;

The main character was originally a painter doing a portrait for a woman as some sort of wedding present and they were fooling around.

He eventually left where he was and awakened some sort of power to turn into a dragon, or a dragon soul found him? It's hard to recall.

In one of the later books, he is imprisoned and partially lobotomized and the dragon part of him has to heal the damage.

There's another guy who can also turn into a dragon who gets severely burned.

All the people who can turn into dragons grow scales the more they bond with the dragon souls.

The main character winds up living in a cold snowy region.

I'm pretty sure it was a series, but I suppose it could be just a single book.

Lord of Snow and Shadows by Sarah Ash. Tears of Artamon series.

That's it! Thanks!