Thomas Hardy uses a lot of techniques in his writing that give the reader a sense of hopelessness, and darkness for his characters. In his novel, The Return of the Native, Hardy uses a lot of different techniques that seem to carry over to his other works, including a good amount of very dark symbolism and imagery that portrays his fatalistic view on life, he uses irony consistently, he carries a motif of fate and fatalistic ideas throughout the novel, and he uses a lot of metaphorical language. Hardy seems to use all of his techniques and his diction to portray how life is in no way under the characters control, but fate has a great hand in everything.
The most obvious examples of symbolism in this work involve the different marriages going on between the various characters. During the meetings between Eustacia and Wildeve, there is always an element of darkness that seems to show that fate did not want the two to be married, or escape the heath. On a very basic level, the two always meet in the dark, which portrays fates or God's dislike for the two's lusting for each other. This also seems to take place during the meeting between Eustacia and Clym, when they decide to be married. The night in this scene is even darker than usual though, since there is a full lunar eclipse while the dialogue is going on. Then "fate" seems to take the upper hand while they are married, and it destroys both Eustacia's and Cylm's dreams, outside and within the marriage.
The irony in the novel is also portrayed very darkly, and it seems that Hardy is trying to push his ideas on the reader in this sense also. When Clym's mother finally decides to take the first step in reconciliation with her son, she is turned away from the house, and dies on the way home, never getting to make amends with her son. The circumstances by which this scene takes place are very out of the ordinary, and it would seem that Hardy is suggesting that fate has stepped in because the two were not meant to make their reconciliation.