Aub Ehrenfest

The Lord of Ehrenfest - or Aub Ehrenfest - governs the duchy of Ehrenfest, where the events of the story take place. The current Lord Ehrenfest is Sylvester. The Aub and his family reside in a castle in a seperated part of the noble's quarter of the duchy's capital, also named Ehrenfest.

Hundreds of years ago, the territory was conquered by a neighboring lord. The noble with the most mana was chosen as the new lord and named the territory Ehrenfest and became the first Lord Ehrenfest.

From there on, the archduke and his first wife choose the successor from among all the Archduke's children, including those of second and third wives and even adopted children. The main deciding factor for which of the children is chosen as successor is their mana capacity, though skills and gender are also taken into account. Males are generally prefered over females due to the negative effects that large usage of mana during pregnancy can have on unborn children.

The Aub must use their mana to keep the protective barriers of the duchy active every few days, so a duchy will have a hard time compensating for an Archduchess not being able to do so for full the length of her pregnancy, hence the preference of male archduke candidates as successors.

Spoilers from Part 4 Volume 3 During their time at the Royal Academy Lady Gabriele of Ahrensbach fell deeply in love with the son of the fourth's Aub Ehrenfest. Due to her having a rather small mana capacity for an archduke candidate of a greater duchy her prospects of marrying a future Archduke were low, but since Ehrenfest was just a minor duchy with a much lower average in mana capacity among it's nobles, this was not an issue in this case. She used her position to force the marriage through, disregarding what her future husband or his family might wish. She would later give birth to Veronica and Bezewanst and thus this marriage is seen as the root of many problems by some of Ehrenfest's nobles.

At some point before any of his children were born, the sixth Aub Ehrenfest fell ill to the point that his life was in jeopardy. Since he had no successor yet, his brother Bonifatius was trained to take over the position and shown all the secrets that usually on the Aub himself was allowed to know. Thanksfully the archduke made a recovery and later had children.

For some time it looked like his daughter Georgine would become the Archduchess and she was groomed for the position for years, until her younger brother Sylvester was born. This caused a fierce competition to break out between the siblings, which eventually Sylvester won. Since his older sister showed signs of outright hatred toward her victorious brother, she was quickly married off to the neighboring duchy of Ahrensbach, even though it meant that she would only be the third wife of Aub Ahrensbach.

To avoid a similar falling out from the fight for succession to happen to his own children, Sylvester made his firstborn son Wilfried the successor very early on

When the civil war rages in the country, Ehrenfest remained neutral. They were still negatively affected by the purge following the coup, but the duchy took far less damage than any that were directly involved in the war. Due to being spared the worst of the consequences of the war the minor duchy was able to climb in the rankings, become a medium duchy and eventually secure rank thirteen for themselves. But the fact that they only reached this high not because of their own merits, but because other bigger and more powerful duchies have fallen behind makes this position rather precarious.

The knowledge that he would become the archduke no matter what, combined with the coddling he got from his grandmother Veronica who leveraged her enormous political influence to wrest Wilfrieds raising away from his mother Florencia caused the boy to greatly neglect his education. Later he was even tricked into committing a crime against the duchy by a faction of Ehrenfest nobles trying to replace Sylvester with Georgine, which nearly cost the boy his position as a noble alltogether.

While thanks to his new adopted sister Rozemyne the worst was averted and Wilfried even remained an archduke candidate, his guaranteed right of succession has since been revoked, meaning in theory any of the Archduke's children, including his adopted daughter Rozemyne, might become the next Aub Ehrenfest, though Rozemyne has vehemently opposed the very idea of becoming archduchess on multiple occasions.