The Daoine Sidhe and the Fenian Heroes
The Fenian Heroes, those of the De Danann who chose to follow the high kings of Ireland, joined with the fiana and fought alongside their human allies. The Daoine Sidhe did almost the opposite. After the Tuatha De Danann and the Milesians battled and divided up Ireland into the land and the spirit-world, those who became the Daoine Sidhe retreated beneath the earth to live in hollow mounds. Others chose to make their home in the ocean, under the waves.
The Fenian Heroes had a great respect for the Daoine Sidhe despite their different choices. The mounds where the Sidhe made their homes became places of worship for the Fenian Heroes, and so for the people of Ireland. The waves which were said to be inhabited by the Sidhe were held as sacred.
The Seelie and Unseelie Courts of the Daoine Sidhe
In some versions of Irish mythology, the Daoine Sidhe eventually divided themselves into the Seelie and Unseelie Courts. The Seelie (seleighe in old Irish) Court was considered to be blessed or holy, containing those of the Sidhe who were benevolent and generally considered harmless. This was not to say that they would not seek vengeance, but if given the choice between harming and helping, the Seelie would choose to help.
The members of the Seelie Court were said to be fun-loving and mischievous. They loved their games and pranks, but would never take a joke too far. They were known to be kind and generous, and were seen as the champions of the people of Ireland.
The Unseelie Court was just the opposite. They were malicious and tended to be inclined towards evil. They were said to assault travelers at night, often carrying them off into their own world for various purposes. As the Seelie were not always entirely kind, the Unseelie were not always entirely evil. However, if faced with the choice, they would rather cause harm than offer assistance.
The Daoine Sidhe were the last of the Tuatha De Danann to resemble the gods and goddesses of ancient Ireland. Though they generally chose to take human form, they could also appear as much larger or much smaller than the average person.
In time, the Daoine Sidhe would dwindle further away from their origins, eventually becoming the Heroic Faery of the Faery Lineage.