If you liked the Harry Potter series or Rick Riordan's Last Olympian books, you will probably like Henry H. Neff's "The Tapestry" trilogy.
In Hound of Rowan, Max McDaniels finds an alcove in Chicago's Art Institute which contains an old tapestry. The tapestry begins to glow. When Max leaves the alcove, he discovers a letter in his pocket which says he is invited to attend the Rowan Academy in New England. It is an exclusive school for people with special talents. And the alcove is no longer there.
Immediately, Max notices that he is being stalked by strange people and is nearly kidnapped. As it turns out, more than forty other Potentials have disappeared. Max makes it safely to Rowan Academy where he begins his training. He is paired with a mythical animal called a lymrill. It is about the size of a wolverine with steel quills. To make matters just a bit more touchy, Max falls afoul of the school bully, Alex.
The story has the flavor of Celtic mythology without borrowing heavily from it. The lymrill is an animal invented by the author, but it feels right in the story.
Max is a rough-cut main character, not always following the rules, somewhat scrappy (yes, he was provoked), and occasionally a bit unexpected. He gets in quite a lot of trouble and still manages to save the day in superhero style.
In this first book of the trilogy, we are introduced to a world-class villain. I have no idea how the good guys are going to defeat him, but I'm willing to read more in order to find out.