Hardy develops Randolph's character in two very interesting though contradictory ways: (1) name symbolism for what Sophy hopes he will be; (2) behavior and surname symbolism for what he is.
Randolph's name is Old English and means "wolf shield." Two important symbolic traits of wolves are their loyalty and their loving relationships amongst themselves. A shield is a protector and defender. Sophy meant Randolph to be her loyal, loving son who would also be her defender and protector when her village ways clashed with London's polished, sophisticated ways. Sophy was terribly disappointed because what she was got was a son who criticized and judged her:
'Has, dear mother--not have!' exclaimed the public-school boy, ...'Surely you know that by this time!'
The symbolism of Randolph's surname, Twycott, is the more telling of the view of Randolph that Hardy develops. "Twy" is Old English for "two." "Cott" is an Old English nick-name for a man who is cold and hard-hearted. Twy- is important because it indicates that the surname symbolism of Twycott applies to both Vicar Twycott and his son Randolph: both Twycotts are cold hard men. Randolph's behavior from the beginning corroborates this symbolism since everything he does toward his mother is cold and hard-hearted, from criticizing her country speech to demanding she not marry someone who is not a gentleman to riding like a sentinel guard atop her funeral train as she takes her last ride to her country village home. Hardy thus develops Randolph as a vain, hard and cold boy, then man, who is not above cruelty to his mother:
from the mourning coach a young smooth-shaven priest in a high waistcoat looked black as a cloud at the shop keeper standing there.