In the 11th book of the Aeneid, the Volscian shield maiden Camilla, Diana’s favourite, is slain in battle by the Etruscan Arruns. Opis, a divine servant of Diana, is sent out by the goddess to exact divine retribution. When she sees Arruns, she utters:
‘cur’ inquit ‘diversus abis? huc derige gressum,
huc periture veni, capias ut digna Camillae
praemia. tune etiam telis moriere Dianae?’
Why do you stray? Step this way, come here, you who are to perish, that you may receive the reward worthy of Camilla. Shall also you die by the shafts of Diana?
Servius was struck by a deep personal note, an “immense bitterness” (ingenti amaritudine), in the last sentence, and claims that Opis “grudges” (invidet) Arruns the honourable manner of his death. Servius supposes that the reference of etiam, “also”, is to the many children of Niobe, who famously perished by the hands of Apollo and Artemis. However, Opis may have had personal causes to reflect in this manner.
Who is Opis? As Herodotus recounts, in very ancient times, a group of young women arrived from the land of the Hyperboreans to the island of Delos. According to esoteric mythological accounts, which Herodotus may have known but if so chooses not to express plainly, they came to assist at the birth of Apollo and Artemis, and to nurse the gods in their infancy. Callimachus, however, probably considering such stories to be not only tasteless but sacrilegous (the gods being eternal), instead claims that they were the instigators of the Hyperborean tradition of bringing offerings to the temple of Apollo on Delos. Herodotus claims that there were two of them, Opis and Arge, but Callimachus holds that they were three, giving their names as Opis, Hecaërge, and Loxo.
Later, these women appear as part of the divine retinue of the goddess Artemis. It is not told in extant sources how this transformation from mortal maidens into immortal servants of the goddess came about, but Claudian touches briefly upon the matter:
Iungunt se geminae metuenda feris Hecaërge
et soror, optatum numen venantibus, Opis
progenitae Scythia: divas nemorumque potentes
fecit Hyperboreis Delos praelata pruinis
There join them [i.e., the retinue of Diana] the twin sisters Hecaërge, terror of beasts, and Opis, deity beloved of hunters, Scythian maids; their preference for Delos over the Hyperborean frosts made them goddesses and queens of the woods. (Platnauer, Loeb, slightly revised.)
Opis is allowed moments of indivdual glory in this function. In Claudian, she is the charioteer of Artemis on a particular mission, but only in the Aeneid is she allowed to speak. The line that made such an impression on Servius may not be a disinterested reflection on the unworthiness of the victim Arruns, but owe to a personal reminiscence. Fragments of a tale of Opis’s individual fate before meeting Artemis are preserved in a damaged papyrus of Callimachus’ Aitia; in pseudo-Apollodorus; and in the Homeric scholia, which attribute the tale to the poet Euphorion. Apollodorus writes:
ὁ δ’ Ὠρίων, ὡς μὲν ἔνιοι λέγουσιν, ἀνῃρέθη δισκεύειν Ἄρτεμιν προκαλούμενος, ὡς δέ τινες, βιαζόμενος Ὦπιν μίαν τῶν ἐξ Ὑπερβορέων παραγενομένων παρθένων ὑπ’ Ἀρτέμιδος ἐτοξεύθη.
But Orion was killed, as some say, for challenging Artemis to a match at quoits, but some say he was shot by Artemis for trying to force himself upon Opis, one of the maidens who had come from the Hyperboreans. (Frazer, Loeb, slightly revised.)
Alluding to the legend in the version of Callimachus and Euphorion, Opis’s address to Arruns would include an implicit comparison to Orion, the Great Hunter, in her experience the first victim of the arrow of Diana, and intimately connected with her own personal fate – which was not to be ravaged and bear the child of Orion, but to preserve maidenhood eternally in the service of the goddess.
“Famous Hyperboreans”. Nordlit, 33 (= P. P. Aspaas et al., eds., Rara avis in Ultima Thule: Libellus festivus Sunnivae des Bouvrie dedicatus), 2014, pp. 211–23.
 Verg. Aen. 11.855–57.
 Hdt. 4.35.
 Serv.Dan. Aen. 11.532, 11.858; cf. Phanodic. FGrH 397 fr. 5.
 Call. Del. 291–98.
 Call. Del. 292.
 Claud. Cons.Stil. 3.253–56.
 Claud. Cons.Stil. 3.277, 292.
 Call. Aet. fr. 186.26–30 Pfeiffer (POxy. 19.2214); [Apollod.] 1.27; Euph. fr. 103 Powell ap. Σ Od. 5.121.