James, Anna (Anna Lois). Chronicles of Whetherwhy #1

"When Juniper discovers she is an Enchanter, she must leave behind everything she knows to begin studying at the Thistledown Academy. And when her twin brother, Rafferty, begins an apprenticeship at a nearby bookbinder to be close to her, he too has adventures of his own. As Juniper learns how to wield enchantment and hone her magic, Rafferty becomes involved with a mysterious secret society that meets after dark. Monsters are creeping out of the shadows and dangers lurk in unexpected places"--Provided by publisher