Final answer:
Epic narratives consistently employ multiple plot lines, recognition scenes, and scenes of suffering, alongside episodic content that enhances the main story. Themes of personal and divine struggle, as well as the pursuit of excellence and immortality, are also recurrent throughout epic stories.
Step-by-step explanation:
The devices that occur consistently throughout the plot of an epic include various narrative techniques and structural components that add depth and grandeur to the storytelling. In epics like Homer's The Iliad and The Odyssey, these devices include but are not limited to the use of multiple and interwoven plot lines, recognition scenes, and scenes of suffering, which help in developing a rich and complex narrative structure.
Epic poetry should also have as many kinds as Tragedy: it must be simple, or complex, or "ethical," or "pathetic." Additionally, relevant episodic content is used to expand on the main plot and to provide additional context or backstory which enriches the overall narrative. Devices such as the struggle against personal limitations and the divine, the representation of arete (excellence and moral virtue), and the quest for immortality, as seen in The Epic of Gilgamesh, are thematic consistencies that recur within the epic genre.