Franz Kayßler was born into a life of luxury, heir to the biggest fortune in the capital one of the world's biggest economies. Tragedy struck him at an early age when his parents both died in a skiing accident - however, despite this loss Franz was looked after by his Great Aunt Claudia and lived a happy, carefree life.
In his late teens Franz made a discovery which shattered his life. Shortly about to inherit the family fortune he set about investigating the paperwork and discovered a carefully manufactured fiction surrounding its origin. The vast sums of money which had given him a life of leisure had secretly grown from the bloodstained coffers of a despicable relative, who served as a Nazi "superhero" called Grösshorn Eule. The Kayßler family may have spent its wealth for generations on business and charity, but it started with genocide and war.
Disgusted to discover his riches had been built generations before on suffering, Franz had a crisis of faith. He left his family behind and went to seminary to train to become a priest, hoping to cleanse the sin that he felt stained his ancestry.
Away at seminary, though, Franz had time to think about what he could do to cleanse his family name. After a couple of years of soul-searching he left his induction into the priesthood and, with the aid of his family fortune, set out around the world to meet the finest martial artists, acrobats and escape artists. He wanted to make sure that his family would be remembered not for masked fascists but for true masked heroes - as Das Ritter Von Nacht, or "The Knight Of The Night"
He built a chainmail and lycra outfit inspired by the stories of Gotham City's Batman, and armed with his mastery of martial arts from multiple continents (having specialised in both Muay Thai and Capoeria in his travels) he returned to Berlin, made peace with his Great Aunt Claudia, and took up his place as the head of Kayßler GmbH, the family megacorp he had deserted years ago. Now, though, he had a use for their "dirty" money - to build him an urban fortress in their HQ from where he could launch his fight against crime.
Franz is not alone in his fight: he is joined by Heidi Köstli, a teenage girl who tried to pick his pockets whom he took under his wing. Once a street punk forced to choose between thievery or prostitution, she has found a new calling in life as Die Eule-Kind, or "The Owl Chick", a blue-and-red spark of craziness who may well turn the imagery of Grösshorn Eule into something heroic and finally cleanse the Kayßler family name once and for all.
Heidi now lives with Franz and Clauda in the Kayßler Building; the two of them have become her legal guardians.
To people not familiar with his costumed alter-ego, Franz would probably be described as charming and care-free if perhaps a little conservative. Always quick with a smile and the offer for male friends to join him at a sporting event or female friends to join him for dinner, Franz endeavours to be everyone's friend and even his business rivals usually acknowledge him as a good man.
Franz is a practising Roman Catholic. He is also a strict non-drinker, claiming the last time he drunk alcohol was communion wine when still training to be a priest.
Franz is every bit the stereotypical German. He is blonde, blue-eyed, tall and muscular - and considered quite handsome. (His Great Aunt often tells people that "He was too pretty for the priesthood anyway".) A scar on his right cheek, inflicted by Die Mauer, is publicly said to have been gained fencing; under his clothes, however, he has several more scars from training and field operations.