 In the first three seasons, this is Michael Kausch in the role of Dr. Giselmund Arnold, later Jenny Gröllmann as Isolde Isenthal "Issi" and finally Stefan Reck as Dr. Bruno Pelzer.They are often idealistic, while at the same time more conventional and serve as antagonists of pragmatic, but unconventional Liebling.Most funny dialogues in the series result from this contrast.