He made converts. Hopefully he did not proselytize or impose any fear upon the pagans as to their state of idolatry.
Catholic Online: Tradition states that Rupert was a scion of the Frankish royal Merovingian family. He was also the uncle of Saint Erentrude.
Rupert was bishop of Worms until around 697, when unbelievers in the vicinity of Worms exiled him from the city. He was sent as a missionary to Regensburg in Bavaria. There, he may have first baptized Duke Theodo of Bavaria, whose permission was necessary for further missionary work, and then baptized a number of the nobles. More here.