In 1873, Fountain moved from El Paso to Mesilla with his wife and their five children. There he became a lawyer, using his fluent Spanish to good advantage in jury trials. Fountain was appointed assistant district attorney and also served as probate judge and a deputy court clerk. In 1877, he founded a newspaper, the "Mesilla Valley Independent", which was issued in both English and Spanish. He also founded the Mesilla Dramatic Society and the Mesilla Valley Opera House, now The Fountain Theater, both originally operated by his family.