Talk with Medea, ''help me get to Northern.'' She will firsts enlist the help of Gracie from you. You get Gracie's help by simply fucking her.
Medea then asks for the ruby, find the ruby by ''exploring.'' this will open a location called Mountain Peaks.
Go to Mountain Peaks, do the quiz. Get enough answers correctly and you will get the ruby item in your inventory.
Go back to Medea, ''Help me get to Northern.'' she will say that she now has everything she needs to help you cross and 'if you're ready to go, come talk with me again.'
Click on Medea again. ''Help me get to Northern.'' now she says she will meet you alongside Gracie at the Ravine.
Go back to the overworld and click on the Ravine Edge.