Celtic paganism was subjected to a Christian overlay; this is similar to what happened to the religions traditions of Western Africa, which resulted in several syncretic belief systems, including Voodoo. Today, we only have shards and remnants of the Old Ways; the times when Morgan Le Fay was a goddess, not a demon. Somewhere in the halls of that collective memory, hidden inside long forgotten nooks and crannies, there awaits amazing beasts aplenty:
Specifically, the Aos Sí.
The Banshee (Old Irish: ban síde), means “woman of the síd”. These creatures announce immanent deaths through their wailing and shrieking.
There are other spectral ghouls among the Aos Sí; for instance, the Scottish Bean Nighe: the washerwoman who is seen washing the bloody clothing or armor of an individual who is certain to die.
On the protective side, we find the Leanan Sídhe: the “fairy lover”, as well as the familiar animals, the Cat Sìth, the fairy cat; and the Cù Sìth, the fairy dog.
However, on the darker side, we find the the Sluagh Sídhe—”the fairy host”— a crowd of airborne spirits; these are the remnants of the damned, angry spirits who are more than happy to steal away the souls of the innocent.
So, to honor Beltane, consider the rituals that mark this day – from bonfires to Mayday baskets (make sure the flowers are yellow), from jumping through flames to appease the angry Aos Sí to visiting holy wells.
Whatever ritual you choose, have a happy Beltane/Mayday!
(And keep the angry Aos Sí at bay…)