Mathis was known as a short woman with untamed brown hair and a love of
Parisian fashion. She had a famous temper and an unbending will. She was driven and would do all she could if she was convinced she was right.
Mathis was a
spiritualist with
mystical bents. Her scripts featured many heroes with a Christ like demeanor. She believed in
reincarnation and always wore an
opal ring when she wrote, convinced it brought her ideas. She had been a sickly child and believed she healed herself through her sheer force of will. She believed everything was mental and everyone had certain vibrations stating,
"If you are vibrating on the right plane, you will inevitably come in contact with the others who can help you. It's like tuning in on your radio. If you get the right wave-length, you have your station."
Mathis and Rudolph Valentino remained fast friends after
Four Horsemen. While their relationship was never believed to be romantic in nature, there is evidence from both sides that the two enjoyed a very strong and loving platonic friendship. Accounts state that Valentino regarded Mathis in a motherly way, calling her 'Little Mother,' and that she thought of him as a son (despite only being 8 years older).
Nita Naldi, who worked with the pair on
Blood and Sand, said of them,
"She mothered Rudy, and my dear she worshiped him and he worshiped her".
Mathis looked after Valentino's welfare at Metro, making sure he got the best parts and was taken care of. She also bailed him out of jail when he was arrested for
bigamy when he married
Natacha Rambova without finalizing his divorce to
Jean Acker.
Though the two were inseparable, their relationship became strained during Valentino's marriage to Rambova. When Mathis submitted a script for
The Hooded Falcon, one of Valentino's pet projects, the couple deemed it unacceptable and asked to have rewritten. Mathis took it as a great insult and broke off all contact with Valentino.
After Valentino's marriage with Rambova ended in
1925, the two friends reconciled at the premiere of
Son of the Sheik when Valentino spotted Mathis with friends. It was said to be a tearful reunion and the pair began to act as if old times. As Valentino began to feel ill in
1926 she was by his side and encouraged him to slow down and take some rest. True to her belief in the supernatural, Mathis reported seeing an apparition of Valentino in her living room the night he died.
When Valentino unexpectedly died in August 1926 Mathis was said to offer the most touching quote by saying
"My long association with Rudolph Valentino endeared him to me, as he has become endeared to everyone who knew him, my heart is too full of sorrow at this moment to enable me to speak coherently. I only know that his passing has left a void that nothing can ever fill in that the loss to our industry is too great to estimate at this time."
Due to estate issues Valentino was left without a burial place, so Mathis offered up what she thought would be a temporary solution: to lend him her spot in the family crypt she had purchased in
Hollywood Memorial Cemetery (now called the
Hollywood Forever Cemetery). However, when Mathis herself died the following year, the arrangement became permanent. Instead of 'evicting' Valentino, Mathis's widower, Sylviano Balboni, moved his casket to the niche next to hers, and sold the remaining crypt to Valentino's family. Mathis and Valentino repose side by side to this day.
Before her death Mathis and Balboni along with a committee of local
Italians had tried to create an Italian Park on Hollywood Avenue in Valentino's memory. However she passed on before anything was officiated and the project was eventually forgotten.
Mathis remained close with her grandmother and her mother. In December 1924 she married
Italian cameraman and later director Sylvano Balboni, whom she met on the set of
Ben-Hur in
Italy. They remained married until her unexpected death. After her death he moved back to
Italy. They never had any children.