Question: is heimdall aesir or vanir?
Answer: Heimdallr advises that they simply dress Thor up as Freyja, during which he is described as hvítastr ása (translations of the phrase vary below) and is said to have foresight like the Vanir, a group of gods: Benjamin Thorpe translation: Then said Heimdall, of Æsir brightest — he well foresaw, like other Vanir —