If a location has 2 different color markers (Ruler & Serf), what happens if the Serf player influences there?

The existing Serf will be 'promoted' to Ruler, reinforced by a Subject of the same color due to the extra influence added to that location. The former Ruler is 'relegated' to the Serf position, taking over the existing landscape (if any). The location type (Outpost / Farm /Town / Feudum) is not relevant.