I think those are just randomly generated courtiers. There's a lot of systems in place to prevent or at least minimize the ability of Argonians to change over.
Not sure, actually! I've never really interacted with the Worm Cult.
Why can't argonians be non-hist?
"Because of the birthing rituals in Black Marsh and the hatchlings' dependency on the Hist, it is considered rare for a hatchling to be born out of the province and away from the connection of the trees: but it is possible. One Argonian, named Ja-Reet, was born into slavery in the province ofMorrowind, and was deprived of the Hist as a hatchling, but eventually returned to Black Marsh with a Dunmer woman that he had married. Although able to function in other societies, he was described as "disadvantaged", or maladjusted, in Argonian society and unable to understand Argonian social cues and body language; this of course was blamed on his lack of connection to the Hist."
-http://elderscrolls.wikia.com/wiki/Argonian
Sure, make it harder to do, but it seems like it should definitely be possible for the player to switch on their own choice.
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