I created a series "bible" in order to keep track of everything and everyone in the Chronicles of Ylandre universe including genealogies of the current members of House Essendri. For the sake of minimizing confusion, I've posted abridged versions of those genealogies here. Please keep in mind that some details may change or be corrected with regards characters whose books haven't been written yet. And not all the information will make it into the books either. It just so happens that knowing my characters' backgrounds and how they are related to the Ardan of Ylandre and/or to each other helps me keep my characterizations as consistent and credible as possible.
Rohyr, Dylen and Imcael Essendri are sons and/or grandsons of an Ardan:
1. Rohyr through both his parents, Keldon and Dyrael, since they were first-degree cousins whose sires, the Ardan Joren and Prince Raval were brothers.
2. Dylen through his sire Dyrael, Rohyr's birthing father, who was the only child of Prince Raval, the Ardan Gilvreth’s second son and the Ardan Joren's younger brother.
3. Imcael since he is the second son of Rohyr's grandsire the Ardan Joren. His sons Mahael, Ronuin and Tyrde are first-degree cousins to Rohyr.
Keiran & Reijir Arthanna and Keosqe Deilen are related to Rohyr through both parents:
1. Keiran & Reijir's sire Rodeth was descended from a younger son of an Ardan and was therefore cousin to Rohyr's parents. On the other hand, their birthing father Liande was a grandson of the older half-brother of the Ardan Joren through the Ardis Levare, his birthing father and the Ardan Gilvreth’s consort, which makes Rohyr their cousin once removed on that side of their family.
2. Keosqe's parents Emris and Taivon are first-degree cousins whose respective sires were the previous Herun of Sidona and his brother. The Deilens are descended from the youngest son of an Ardan.
The others are related to Rohyr through one parent descended from a younger son or brother of an Ardan:
1. Yovan Seydon's birthing father Evran and his son Rysander's grandfather is the only child of Andrion, the younger brother of the Ardan Gilvreth Essendri, Rohyr's great-grandsire, which makes Yovan a second-degree cousin to Rohyr’s parents and Rysander a third-degree cousin to Rohyr. Evran married Laval Seydon, a well-to-do, untitled aristocrat from Ilmaren and chose to take his surname. Yovan espoused Mered Cordona, a scion of one of the richest families in Ylandre whose network of banks and financial institutions spans most of the North Continent.
2. Aeldan & Ashrian Mithani are related to Rohyr through their birthing parent Kaiden whose grandfather was also the
younger brother of Keosqe Deilen's great-grandsire. Kaiden's father married one of Edessa's wealthiest barons, Lord Desir.
The marriage produced three sons of whom Kaiden is the youngest.
3. Ranael Mesare's birthing father Mihlon was the second son of Lord Desir and the older brother of Aeldan & Ashrian's
father Kaiden which makes Ranael and the Mithani brothers first-degree cousins and also third-degree cousins to Keosqe
Deilen. Mihlon's eldest brother, the current Lord Desir, is without issue. Therefore the title will one day pass to Ranael since his older brother is a prelate of the Church.
4. Eiren Sarvan traces his line of descent through his birthing father Mylan whose own father was the younger son of a baron who forfeited his and his descendants' claim to the title when he wed a physician and commoner against his parents' wishes. Because of this, when his older brother died without issue, the title went to a distant cousin instead. Mylan’s spouse and Eiren's sire Aloir was from the upper gentry, the only son of a wealthy landowner.
5. Jareth Hadrana claims kinship to Rohyr through his birthing father, Alvare, widower Heris of Ziana, whose grandfather Nadeth was the younger brother of the grandsire of Desriq Calanthe the Herun of Losshen, thus making Alvare and Desriq second-degree cousins.
6. Zykriel & Gilmael Calanthe's sire, Desriq, the Herun of Losshen, traces his bloodline to an Ardan's younger brother. He is also a second-degree cousin of Alvare, Heris of Ziana, which makes his sons and Jareth doubly related by blood.
7. Shino Essendri's late sire Zabreth was a direct descendant of an Ardan's youngest son. In addition, his birthing father's sire and Laval Seydon were second-degree cousins, which makes Shino and Rysander Seydon cousins twice over.