Spoilers: I'm going to stick to Basics for a while, even though they contain spoilers...
AKA: Efram Zarelle, fire pixie (Manfred and Wolfram)
Age: ~43 in year 0 (45 in PW)
Looks: green-blond hair, green eyes - looks like Wolfram. An adolescent, he grows from 4'10" to 5'6" during these years.
Character: Genius. Impish, effervescent, irrepressible.
Special skills: Fire healer, majutsu & houjutsu defense. Scholar.
Family: Only joint child of Manfred von Bielenfeld and Dionne Zarelle, a professor of majutsu theory at the Bielenfeld Institute, from the Krist Fens. Efram's parents never married. Dionne married another professor from Krist, of houjutsu defense, when Efram was a baby. But Manfred lived only a few blocks away, and Efram visited at whim. Efram has two half-siblings on Dionne's side, plus half-siblings Wolfram, Kieran, Bertram, Avram, and Margritte on his father's side, plus worshipful step-brother Dietrich via his other step-father, Aldrich. Efram feels particularly attached to Bertram, because Bertram's mother Dierdra was Dionne's sister - Bertram's as close to a full brother as Efram's ever going to get. Efram was legitimated as a von Bielenfeld during PW.
Poor Efram has four professor parents, pushing him to excel in four different academic degrees. He hasn't finished any yet... He's also Head of the Horde of Bielenfeld-Gratz aristobrats, a key leadership role. He hosts and polices not only family occasions, but also parties for the Bielenfeld plantation brats during squire conferences.
Efram's stepfather kicked him out during PW, and he ended up living with Wolfram mostly for the next few years. He and Greta really hit it off, though the Mazoku/human aging differential means their days as close friends are numbered. After Aldrich and Manfred marry, Efram spends more time at Castle Bielenfeld with them. Aldrich's grooming him to be Dietrich's alternate as heir.
Efram's extraordinary majutsu skills, scholarship, curiosity, and raw impishness, tend to get him in over his head.