Little Father Time doesn't show up until really late in the novel, but boy does he make his role count. From the moment we meet the child of Jude and Arabella, we know something is a little off. He gets his nickname because he is "Age masquerading as Juvenility"—in other words, Little Father Time may be biologically a child, but spiritually, the kid is as old as Jiroemon Kimura. Jude's son by Arabella. He does not meet his father until Jude and Sue adopt him as 'an intelligent age.' The boy's nickname arises from his serious, almost morbid, nature.
Little Father Time in the Essays