After completing a directorial apprenticeship at the municipal theatre of his native Wuppertal, from 1951 Pörtner studied philosophy, plus German and French literature, at the University of Cologne.
His short stories and novels very often deal with social outsiders and the disadvantaged – as a young man, he himself became physically handicapped during World War II.
His interest in avant-garde theatre led him to embrace the theories of Jacob Levy Moreno, Antonin Artaud and Erwin Piscator.
In addition, through his stage work as director and playwright he fell under the charm of commedia dell'arte, as well as the absurdism of Kurt Schwitters and Alfred Jarry.
In 1963 Pörtner wrote the interactive play Scherenschnitt oder Der Mörder sind Sie in which the audience takes a leading role.