Mathis is the head of the D'Amaris House, one of six ruling houses on Serenno. He had four children with his wife Selesme: Edmon, Jacques, Solange and Luc. His immediate successor is Edmon, followed by Edmon's son Julien, then to Jacques and his children, and so on.
The D'Amaris family head is a very powerful man. Little is known about him outside (and even inside) his family, and he keeps a tight circle. To the public he comes across as a respectable man who full-heartedly commits to "speak softly and carry a big stick."
► 64 ABY: Mathis is born
► 82 ABY: Mathis marries Selesme, a wealthy woman from Coruscant
► 82 ABY: Selesme gives birth to his first child, Edmon
► 83 ABY: Selesme gives birth to his second child, Jacques
► 86 ABY: Selesme gives birth to his third child, Solange
► 88 ABY: Selesme gives birth to his fourth child, Luc
► 120 ABY: Mathis officially changes the succession tradition, putting Jacques behind both Edmon and Julien
SKILLS & ABILITIES
As the D'Amaris head, Mathis' assets are listed under the D'Amaris family lore write up (link).