The nature of his origin and rise to the throne is disputed; some scholars regard him to have been a member of the incumbent Bosporan Tiberian-Julian dynasty whereas others believe him to have been a barbarian warlord who usurped power.

[1] Ivan Alekseevich Astakhov considers it "undoubtable" that Theothorses was a member of the Sarmatian or Alan aristocracy and seized power in the Bosporus after defeating a Gothic invasion in the middle/late 3rd century.

[6] The French genealogist Christian Settipani believes Theothorses to have been born c. 260 as a son of the previous king Rhescuporis V (r. 240–276) and a nephew of Teiranes.

[1] An inscription from the last few years of Theothorses's reign from the city of Theodosia by its governor, Aurelius Valerius Sogus, indicates that the city was at this time incorporated into the Roman Empire (due to Sogus using imperial titles and paying homage to the incumbent emperors rather than to Theothorses and calling Theodosia a "province").

Combined with brief mentions of a Bosporan campaign in the Transcaucasus and Asia Minor in later sources,[1] possibly taking place in 292–293,[4] Sogus's inscription was interpreted by Benjamin Nadel in 1977 as indicating that Theodosia had temporarily been incorporated into the empire after Theothorses attacked Roman possessions and was defeated.