Years before the start of the series, August was sought out by Rafal to give him the answer to how Evil could finally win against Good. August then created the Reader Prophecy, and in return Rafal gave him a position at the School for Good teaching History. His half sister, Evelyn, was also given a position at the School for Evil teaching History at August's request. Evelyn was thrown out the school for spying on students, and August took over both classes.
August has silver hair and bright, hazel eyes. He wore a shamrock green School for Good male suit.
Although he could not see, August could see the future.
When Agatha and Sophie arrive at the School, Professor Sader takes notice of both girls. Agatha also thinks of him as a fatherly figure to her since she grew up without one. He shares some of his visions with Agatha and Sophie, aware that their presence at the School could have a massive effect on both the world of fairy tales but also the girls' home village of Gavaldon. His help, however, comes with a price for him; the very act of looking into the future (or the past) ages him physically, and weakens him.
He appears in only one scene in A World Without Princes, where he allows Agatha to see part of his sister's actual past while she was a teacher in the School for Evil. He warns Agatha that Evelyn will know that Agatha has seen this, and will retaliate in some way, but he believes Agatha needs the information.
He also only appears in one scene in The Last Ever After, but this is a much longer scene where he reveals to both Sophie and Agatha the history of their mothers, and their actual relationship to each other. He also admits that he does not know the end of their story, as his visions only go to the moment of his sharing the secrets of their mothers and their own births and early childhood. He admits that the fate of their world, and of the relationship between Good and Evil depends on their choice, which he cannot foretell.
In The Ever Never Handbook, it is revealed that Professor Sader sent Deans Dovey and Sophie a note before his death, instructing them to accept Nicola of Woods Beyond into the School for Good and Evil, as 'her acceptance to our school will play a crucial role in its future survival.'
In the fifth book of the School for Good and Evil series and the second in the Quests for Glory series, Professor Sader is referenced throughout the book. He is told about in a story and Agatha uses one of his books by influence from the Storian. At one point he is believed to be the father of Rhian and Japeth.
Evelyn was jealous of her brother's power, and told Rafal he should not put his faith in him. She also forbid the reading of his book in the School for Girls