Middle Reader or YA novel, at least two books in series, possibly three. Cover looked like a page from a book with ink handwriting and back of a man walking away with a cloak on. About a boy who is working for an adult man who transforms into a monster.

[Natalie]

Middle Reader/YA novel Late 90s or Early 2000s, definitely at least two books in the series, possibly three. The cover looked like a page from a book with ink handwriting and back of a man walking away with a cloak on. About a boy who is apprenticed or working for a young adult man who transforms into a monster. And they are trying to protect the city from the monster. Possibly there are rings drawn at the start of each chapter.

[Becca]

The Book of Dead Days by Marcus Sedgwick?