Epitome from Nagy 2015§§103:
Menelaos seems to be idiosyncratic in his arrivals at sacrifices. A striking example is the passage here at I.02.402–429 where Agamemnon sacrifices an ox to Zeus, I.02.402–403, 422, and makes a wish-in-prayer, as expressed by the verb eukhesthai, I.02.411, that he will conquer the city of Troy, I.02.414–415, and kill Hector together with as many other enemies as possible, I.02.416–418. To attend this sacrifice as well as the feast that follows the sacrifice, Agamemnon invites six heroes, I.02.404–407. But the hero Menelaos is not included in this group of six. Nevertheless, Menelaos does manage to attend, arriving as the seventh hero, without having been invited to the sacrifice, I.02.408–409: rather, he comes automatos, which is conventionally interpreted to mean ‘of his own accord’, or, to put it into popular idiom, ‘automatically’, I.02.408. But the reason that is given here to explain why Menelaos comes automatos is uncanny: it is because, the narrative says, Menelaos can read the mind of his brother, I.02.408–409.