Tokugawa Ieyasu had been with him for many years when he was a child, when Tokugawa Ieyasu was still a hostage of Imagawa Yoshimoto. It seems that Bendo's father died to save Tokugawa Ieyasu's father, Matsuhei Hiroshi (formerly known as Matsuhei Yuankang in Tokugawa Ieyasu), so Bendo's mother has been educating him to be as loyal to the Tokugawa family as his father. When he was a child, Bendo was called Bendo Shiro, and Zhongsheng was named after him by Tokugawa Ieyasu. Benedict has rescued Konka from danger many times, so the relationship between them is not comparable to that of ordinary courtiers. I saw it in Yamaoka Sōhachi's Tokugawa Ieyasu. You can have a look if you are interested.