Final answer:
There is no information in the provided texts regarding what Thetis first thought of Hephaestus, and without additional context or direct sources, a factually accurate response cannot be provided.
Step-by-step explanation:
The question appears to relate to a mythological or literary figure, based on the provided text, but there is no clear connection to Thetis and Hephaestus within the provided excerpts. The information given primarily discusses Hephaestus in the context of the Kabeiroi and does not specify Thetis's initial thought about Hephaestus.
Therefore, without additional context or a specified source that directly mentions the encounter between Thetis and Hephaestus where Thetis misconstrues him, it is not possible to provide a factually accurate response. The passage also includes an excerpt from a story involving characters named Aristomenes and Socrates, but this does not relate to the original query about Thetis and Hephaestus.