Alex Fierro is a gender-fluid einherji, a child of Loki, and an astonishingly powerful shapeshifter. When he first arrives in Hotel Valhalla—identifying as male at the moment—he turns into a cheetah, destroys his room, and attacks his new hall mates. Later, she (female now) transforms into a weasel and tries to escape the hotel. She finally appears in her human form: a hauntingly attractive teenager of slender build with facial features that closely resemble Loki’s, minus the scars. She wears layers of pink-and-green clothes—skinny green pants, a pink-and-green sweater-vest, rose-colored high-top sneakers, and a second sweater, also pink, tied around her waist. Her hair is green with black roots, and she has one dark brown eye and one amber-colored eye.

Alex’s parentage arouses suspicion at first, much as her half-sister Samirah al-Abbas’s did when she first came to Hotel Valhalla. In time, Alex proves herself to be a trustworthy addition to floor nineteen’s group. She’s a fearless fighter, wielding her weapon of choice—a garrote made from a wooden-handled clay-cutting wire—with terrifying efficiency. She helps Sam to see her own shapeshifting ability as an asset and to resist their father’s mind control. After years of being shunned for who she is, Alex holds most people at arm’s length. But she comes to trust Magnus, and ultimately allows him to get closer to her than anyone has for a long time.