"Cogsley can be a real pain in the butt, but he is also the most honest, hard-working robot I know.” - Miskit
Cogsley was an assistent of Silas Charnon (the great grandfather of Emily and Navin) and a main character of Amulet. at the start he was very skeptical about serving Emily and Navin, because they were only kids...
Cogsley is a old model (Vigo Light mentioned it) of his robot. He built the house with his master, Silas Charnon.
"Well, he did build the house with Silas. It's like his baby."- Miskit
In book 4, The Last Council, he and Miskit was carried to a wyvern’s nest. He was pushed by Miskit and smashed a wyvern egg. Then came out a baby wyvern, thinking Cogsley was his mother. In the first book, Cogsley was mean to Emily and Navin but soon afterwards he started getting attached to them.