Fonseca was born in Sacramento, California, and at the age of eleven, he knew he was an artist. He attended Sacramento City College before studying art under Frank LaPeña (Wintu-Nomtipom/Tenai) at California State University—Sacramento. Ultimately, he decided to leave school to pursue his art, his own way. His early paintings were influenced by his Maidu ancestry, depicting traditional basket patterns and dance regalia motifs, and later, scenes from Maidu origin stories and southwestern ancient petroglyph symbols. In 1979, Fonseca began a series for which he is perhaps most renowned, his Coyote series. He placed Coyote in urban settings in non-Native clothing as if to infer that the lives and positions of Native Americans had transformed as much as the Trickster’s had. In 1980, he was granted a fellowship from the Southwestern Association on Indian Affairs, and in 2004, he was bestowed with the Alan Houser Memorial Award.