Avinar of Mindelan was the youngest son and second-to-last child of Piers and Ilane of Mindelan, only Keladry is younger. He was a scholar and teacher at the City of the Gods. He studied in the City of the Gods while Kel was training for knighthood. Avinar also spent some time in Carthak, although probably not much. Considering that he was born some time between his next oldest sister Oranie and Kel, his year of birth can tentatively estimated to be around 440 HE, give or take a year.
He never appeared in any of the novels but has only been mentioned by Tamora Pierce on the internet. While on Progress, it was revealed that Kel had a brother studying at the royal university, and since all three of her older brothers were knights, it is likely that the mentioned brother was Avinar.