Who is Thomas from A Darkness at Sethanon and what is their importance?

Thomas is Pug's childhood friend, and he is married to the queen of the elves. He is part Valheru because of the ancient armor he put on that belonged to Ashen-Shugar. Thomas would like to tell his wife where he is going when he and Pug leave to find Macros, but Pug deters him because revealing their purpose will put their lives in danger.