Arthur wasn't exactly his cousin, but a second cousin since they share a great-grandparent, Fergus.
There was a very good reason Marcel avoided his second cousins, although it's been years since the first incident involving their grandparents, both sides have never gotten along. And Marcel had to admit, his father contributed to that.
After Mattia was banished from the family for killing Albine - his would have been uncle if he was still alive - his sons were not cast away with him since they knew nothing about his crime.
Hatred, they say is contagious and his father had made sure they didn't communicate with Mattias' descendants, treating them as nothing less than an enemy, widening the gap between the family.
Now, a family that is supposed to stand together views each other as nothing but competitors that need to be wiped off.
