Unless stated otherwise, all information herein is taken from AMoL, Prologue.
Eri is a member of Jarid Sarand's personal guard. Bayrd thinks he is the best guard left in Sarand's army. Eri stayed loyal to Jarid for longer than many others, but walked out after Jarid stripped him of his rank, docked his pay, put him on latrine duty, and threatened to cut out his tongue for mocking him.
He is in Jarid's camp when a Bubble of Evil turns all their metal soft.
"Her head? And how, precisely, is someone going to bring you her head? What’s he going to use to cut that head free, Jarid? His teeth?" (Eri reacting to Jarid saying he wants Elayne's head, after all their metal has gone soft)