Although unamed, the fandom has began calling him Lee so I will be refering to him as that throughout this article.
Lee fell down to the underland 2 years, 7 months and 13 days before Gregor did and he was presumed dead or lost by most people, later when Gregor fell down too, he found his father in a gnawer pit, uneaten, he was forced to make guns and equipment for the gnawers and was pretending he could, eventualy he was saved by Gregor and the group in the first book. After he returned to the Overland, he fell ill due to an unknown underland illness and was given medicine in order to aid him. He never fully recovered in the course of the books.

Lee	Information
Name	Lee
Age	Unknown(young adult)
Gender	Male
Species	Human (Ovelander)
Status	Alive
Bond	N/A
Nicknames	Gregors Dad
Relatives	Grace(Wife/Significant Other) Boots(Daughter) Lizzie(Daughter) Margaret(Grandmother)