Since the Diedne are going to play a major role in the saga I am planning I thought I would mention and speak on my ideas about this House as well as the Schismatic war. Let me know what you think of this. This is just ideas that I am jotting down.
Primus: Ailean, a fiery Scottish mage who despises the Tremere.
Favored Tribunal: Loch leagan, Hibernia, and Stonehenge.
Symbol: A triskele.
House Diedne are the heirs to the druidic tradition of the celts. While they are the heirs to the Druid traditon, time has passed the druids by. By the time that the Order is founded the British Isles have been thoroughly Christianized. The old pagan religion had at this time faded from the lands were they had their strength. The house though refused to move with the times, and they stayed pagan. This is partially why they were secretive; as a house they were insular and secretive. This bred distrust and suspicion. In regards to dealing with Mundanes, they wanted to preserve the old pagan views and religion. Hence why during this time, they were sponsors of monks who wrote a number of the myths down.
They however did strongly support the Code of Hermes, and believed in the laws of the code. The old druids, were more then priests, they also served as Judges. As such the house brought this with them, and have a healthy respect for their own laws and codes as well as the Order's. In the grand tribunals they tend to support the non-latin houses, such as house mertina and Bjoronear.
As a house, they are somewhat of both a Mystery cult and True legacy. In that every person has a master-appreintince relationship going back to Diedne herself. But also that there is an inner mystery. Where they learn the secerts of the house, as well as becoming a druid and member of the old pagan religions of the celtic lands.
The schismatic war
The Schismatic war to me repersents a breakdown in politics. The order has a number of both Latin and Non-latin houses. House Diedne and House Tremere have two visions of the Order. One repersents a strong house/weak order(diedne) the other repersents a strong Order and weak house dynamic(tremere). But the larger issue is the non-latin vs latin houses.
No side is without blame for the conflict. House Tremere thought that the House had fallen to infernalism, which is a false for the most part. but the tremere do not know about. Diedne though did not help things when the Tremere asked to watch their rituals, they refused them. They told them that they had no right to view their secrets. The fact that House diedne's rituals were pagan in origin. Both sides would not bulge from their positions, and this increased tensions in already tensious time. The wizard wars did not help. All this resulted eventually into what would be known as the schismatic war.