He is the son of the Margreave of Tenmeadows and apparently attends Briscoe Hall with Boq. He is described as handsome and intelligent with a superiority complex. His role is fairly limited, as in the 2nd section of the novel, he is seen in only a few scenes. He accompanies Elphaba Thropp to Caprice-in-the-pines at Boq's request, but dislikes her from the beginning.
In the last section of the novel, he has since inherited the title of Margreave and is married, though who he married is not revealed. Elphaba comes to him to tell him she killed Madame Morrible, though he doesn't remember Elphaba and seems unconcerned by it. He keeps Elphaba around for his dinner party for entertainment but reveals, before she leaves, that he doesn't believe she actually murdered Morrible.
The unnamed wife of Avaric. Some readers believe she is either Shenshen Minkos or Pfannee. However, she doesn't seem to know Elphaba, and it was later revealed in later novels, that Shenshen became a teacher at St' Prowds school, and Pfannie is the chatelaine of the atelier where Dorothy was sent back to her own world. So this is very unlikely.
In the Musical
There is a character named Avaric, but he is not the same one as in the novel . This Avaric is Fiyero's driver and has no important role. Most of Avaric's character traits from the novel were given to Fiyero.