the mara is a very confusing creature. we first see it on deva loca but apparently it began on manussa? the snakedancers and the manussans and the kinda are similar but not releated i think? it is quite confusing. tegan is great but once lon gets infected we barely see her, which is a missed opportunity, because janet fielding is really great as the conflicted tegan/mara. i like when dr who uses an academic field quite a lot, like planet of the daleks being very biogeographical - here this is very anthropological, so i enjoyed that. lon is a charasmatic character indeed. so ultimately it is not a very good sequel to kinda and the mara but i like it more than kinda in its story elements (study of a society vs conflict between natives and colonists)