Little side chatter about where the sidhe came from, considering putting it with a few other things to try to have a proposed 'history' of the guard and gates, in so much as we know vs what we can guess at with help. But not sure how to organize...
Druids.... They couldn't effect fate(read:freedom of will) but they could conjure the elements and all kinds of fun magical stuff. Anyway
At a time of the Roman conquests of Gaul and Britain the Druids were flourishing as the only unifying institution of the Celts... The Druids were largely suppressed, except in Ireland, which the Romans never conquered
The Druidic practice of human sacrifice may also have encouraged the Romans to suppress the cult... The word Druid is probably related to the Celtic word for oak tree-daur. The oak was in fact sacred to the Druids, as was the mistletoe... Druidic tradition was in par preserved in irish epic for some centuries after its christianization of Ireland and faint echoes in Welsh folklore.
ok so, the Romans moved on them and suppressed the 'magic folk' but started their own studies into magic at the same time, thereby potentially changing the main traditions of magic used by most practitioners thereafter. But ireland, where Jim has drawn on more directly for Mehb and what not, also the sidhe, literally, people of the mounds originate thereafter in Irish legend. I might reedit some of this later, I don't know right now, cutting it very short here though.