During the birth of Mordred Deschain, Nigel brought an incubator into the extraction room in case it was needed. During Susannah Dean's escape, she shot his eyes out because of his resemblance to Andy. After that incident, he helped Susannah and the rest of the ka-tet find their way around Fedic and brought them food.
Nigel's helpful functions were taken advantage of by the infant Mordred, who forced Nigel to bring him small animals including a billy-bumbler for him to eat. Nigel found this very distressing and his circuits blew.