Lairain is an Aes Sedai of the Brown Ajah who was loyal to the White Tower during the The Split. After the White Tower Aes Sedai decide to raise Egwene Amyrlin. Egwene thinks she is likely one of those Aes Sedai that spends their lives roaming the back library stacks.
She is described as short and toad-like.
Reference: (The Gathering Storm, Chapter 46)