I have not found any info on House Ra'Athim at this time. Apart from being based in Ebonheart. ... However Ebonheart is governed by House Dres in the game.
I found info for First Era and Third Era but nothing for the Second Era
The infamous arcane explosion in the Imperial City that happened in the Spring of 2e579 — a night of storms, and trembling terrain — as related by the Chorrol Crier, mentioned by Chancellor Abnur Tharn in his "Eulogy for Emperor Varen" and explained by Lyris of Skyrim in the first volume of her "Chronicles of the Five Companions", and others, I am sure. The “Soulburst” happened at the same time as a big piece of Aetherius fell to Nirn. Coincidence? It was the first major piece of Aetherius to fall in five hundred years.
Then I met the Prophet on 4 Rain's Hand 2e582.
AD - Aradne Oakblossom - Female Bosmer - Stamina Warden
AD - Hirtyaren Grayare - Male Altmer - Magicka Necromancer
AD - Luvinus Sextal (renamed Calvistes Hasana) - Rogue Male Imperial - Stamina Warden
AD - Ma'atharr-do - Male Khajiit - Stamina Nightblade
AD - Urnsyla Aboragia — Female Altmer — Dragonknight
DC - Emnicey Mhejin - Male Yokudan - Stamina Warden
DC - Nelrie Margaux - Female Breton - Magicka Sorcerer
DC - Sheraz Logash - Female Orsimer - Stamina Dragonknight
EP - Frideka Rockbreaker - Female Nord - Stamina Templar
EP - Marzheel Lafmesh - Female Saxhleel - Stamina Dragonknight Shadowscale
EP - Rinris of House Ra'Athim - Male Dunmer - Stamina Nightblade