Ross is the son of a mayor, Tessi is his loyal lady bodyguard.
She's considerably older, and while she is mature and honorable, he is young, wild and fabulous.
Underneath his playful demeanor, Ross is cunning and ambitious.
Tessi has known Ross a long time and is only recently starting to understand how diabolical he can be. She questions his decisions moraly but remains completely loyal and devoted to him; she would go to any length to protect Ross.
Ross is quite the player so it would seem he only flirts with Tessi as a joke (he could have any pretty, young thing he wanted after all) but he cares more deeply for her than anyone, even his father (he just wishes she would let him have some fun), even if he is too depentent on her and takes her for granted.