The illegitimate and rebellious child of influential playwright Ion Luca Caragiale, he was the half-brother of Luca Caragiale, an avant-garde poet who died in 1921, and the posthumous son-in-law of author Gheorghe Sion. Mateiu Caragiale was loosely affiliated with Romanian Symbolism, a figure noted for his dandyism, eccentricity and Bohemianism, and, for much of his life, a regular presence in the intellectual circle formed around Casa Capșa restaurant. His associates included the controversial political figure Alexandru Bogdan-Pitești, cultural animator Mărgărita Miller Verghy, and poet Ion Barbu, who was also one of his most dedicated promoters.