Wolf-Shifter

This story is of a Wolf-Shifter (also called Lycan), or also known as Daire. And yes he can  transform into a wolf at will. He is often mistaken for a werewolf, lycans are advanced wolf shapeshifters who have much greater control over their ability to transform and use their wide range of senses and powers. Daire has also mentioned there is more than one kind of "canine-shifter." Even in human form, a Wolf-shifter possesses superhuman physical prowess that can be used to overpower enemies in human form too.  Their mortal enemies as a species is revealed to be the Lupercus. 

History

Little is known of this type of Fae. A Wolf-Shifter is monogamous by nature and is said to mate for life. Wolf-shifters seem to have an affinity for a warrior life as all shown in the series have been warriors or mercenaries for at least part of their lives. They typically have tattoos of symbols of their race, from past battles and lords whom they have served.

Fae

Fae are creatures that prey upon humans. Whereas humanity consists of a single species (and sub-species), there are a myriad of species within Fae. Most species seem to be similar in appearance to, and of approximately the same intelligence as, humans.

The mechanism of predation varies widely among the species, but typically doesn't involve oral consumption. It appears that most Fae species do eat "normal" food for sustenance, while the predation serves a different purpose. Frequency of predation also seems to be quite varied among species. Predation doesn't necessarily involve killing the prey — the human victim may simply be left temporarily or permanently weak, ill, or mentally or physically damaged.

In recent centuries, the Fae have chosen to hide their existence from the humans, and the humans' stories of encounters with Fae have faded into legend, myth, and fairy tales. Contrary to popular mythical belief, a vast majority of the Fae population are typically humanoid by appearance. Most Fae who can pass as human have infiltrated the human world and live as humans do. Even among their own kind, Fae tend to converse using the dominant human language(s) of their region. The Fae who are incapable of passing, and thus must be kept hidden from the humans, are called Under Fae. Since ancient times the Fae world has been gripped with near endless civil war, this continued until a Blood Sage now called the "Blood King" used his powers to force a truce between the two sides of the Fae, Light and Dark. By the time of the series this peace has lasted for centuries however the Light and Dark collectives still view the other with contempt and suspicion.