The House of Atreus is one of the finest examples of uncontrollable fate in all of ancient literature. The lineage of Atreus is steeped in the spilling of family blood starting with Tantalus and continuing with Agamemnon. However it is Atreus who is responsible for the curse on the family, since he was the one who tricked Thyestes into eating his children. It was this one event that caused the continuation of family bloodshed and forced family members of the House of Atreus to fulfill their obligatory fate upon one another.
The story of the House of Atreus begins with Tantalus, the half immortal son of Zeus. He holds a banquet for the gods and decides to cut up and serve his son Pelops for the gods to feast upon, and Tantalus feels that this sacrifice will be taken in high regard by the gods and Pelops will be restored. He is correct since his son is restored but the gods condemn Tantalus to an eternity of damnation due to his sin of hubris. Later on in his life Pelops has two sons, Thyestes and Atreus, and it is these two that enact the curse upon the family and condemn all future family members to an inevitable fate.
Thyestes was the one who was meant to rule the kingdom of Mycenae, but his brother Atreus took control instead and in an act of revenge Thyestes sleeps with Atreus' wife. Pretending to grant mercy, Atreus invites Thyestes out of exile to a great feast to set aside their differences. At this feast Atreus fools Thyestes into eating his two children, and because of this act Thyestes curses Atreus and his entire family for eternity. It is this one act that seals the fate of Agamemnon and even his wife Clytemnestra to a terrible death.
The story of the Agamemnon focuses around the king of Mycenae Agamemnon as he is set to lead his men in the Trojan War. Before they set sail for Troy Agamemnon's soldiers kill a pregnant rabbit and do not offer proper thanks to the Goddess Artemis. Artemis then withholds the winds so the ships can not set sail and will only do so once Agamemnon has sacrificed his daughter Iphigenia. Stuck with this terrible dilemma Agamemnon decides to be the heroic king to his soldiers and sacrifices his daughter, once again spilling family blood in the House of Atreus.
The men set sail for Troy and it takes ten years for the men to sack the walls of Troy and return home. During this time Clytemnestra has an affair with Aegisthus, who is the last surviving son of Thyestes, and plots to kill Agamemnon to avenge the death of her daughter Iphigenia. Upon returning home, Clytemnestra lulls Agamemnon into a false sense of security by continuously flattering him until she finally traps him in a net in his bath and stabs him to death.
Clytemnestra also kills Agamemnon's prophetic concubine Cassandra, who welcomed the death since she had foreseen both murders. Clytemnestra then boldly proclaims her right to avenge her daughter's death and Aegisthus then takes credit for the murders and becomes king of Mycenae. Unfortunately, since family blood was once again spilled in the House of Atreus by Clytemnestra her exiled son Orestes returns and kills both Aegisthus and Clytemnestra.
Orestes is then tormented by the Furies for most of his life until the gods relinquish this punishment thus ending the curse upon the House of Atreus. Every story about the House of Atreus has one family member killing another thus setting in motion a chain reaction. Another family member feels obligated to avenge their fallen loved ones and kills their murderer. This action causes a never-ending cycle due to the curse placed upon the family. Agamemnon begins this deadly cycle by sacrificing his daughter Iphigenia to Artemis.
This murder then causes Clytemnestra to avenge her dearly loved daughter and kill Agamemnon and Cassandra, who unfortunately had no choice in coming to this cursed house. After the murder of Agamemnon, Clytemnestra pleads for no more evil to be spread in the house since her actions have sealed her inevitable fate. To avenge the death of Agamemnon Electra has her brother Orestes kill both Clytemnestra and Aegisthus, and he is then tormented by the Furies until he is alleviated by the gods.
As it can be seen from all these stories, each family member's obligation to avenge the other just furthers the curse and furthers the spilling of family blood in a vicious never-ending cycle. The House of Atreus' curse began with Atreus killing Thyestes sons and ended with Orestes killing Clytemnestra. When family blood is spilled in the House of Atreus it sparks a chain reaction of vengeful murders, which is carried on for generations. The curse and the obligations of the family members display the inevitability of fate and that it will always be fulfilled in one way or another.