Complex sentence: At school he was nicknamed, "Chuzzlewit," after "Martin Chuzzlewit", which was shortened to, "Tit," then lengthened to, "Titbrain," but Martin still sees this as compliment due to the "Martin Chuzzlewit" origin.
Split into simpler sentences: At school he was nicknamed "Chuzzlewit", after "Martin Chuzzlewit", which was shortened to "Tit", then lengthened to "Titbrain". But Martin still sees this as compliment due to the "Martin Chuzzlewit" origin.