Este é o Quarteto de Companheiros, de Julia Golding.
Para citar Wikipedia :
Each person in the Society has a compatibility with a specific mythical creature. Connie finds out that she is a universal companion, someone who had compatibility with all mythical creatures, and that she is the first one in almost a century. The Society's main purpose is to protect mythical creatures from being exposed to humans, something which has become increasingly harder. Along with this problem, they also have to find a way to stop an evil shareholder shapeshifter called Kullervo who wants to wipe out all of humanity to make way for mythical creatures and he wants Connie's help to do it.