When Teir tells the wolfriders of his life in the rocky plains, I clearly remember him saying his mother was from a wandering tribe and that she stayed only for a while and left. I assumed from the picture they were Go-backs exiled by Rayek. When you look at the pic where Teir's Mother leave him and his father, the elf woman look like Kahvi a lot! A kind of Elf warrior from th outfit.
That explains so many things, like Teir having a troll sword, Teir knowing the Wolriders' death dance when they hear about Skot's death, and of course, Teir knowing Kahvi by sent, etc. Furthermore, Teir being an obvious magic user (like his father), that would explain why she did not give attention to him and left them behind.