In "Source," Irene and Anastasia reunite at a conference center-slash-bar in Alaska. While they are getting to understand each other better, they gaze out the window hoping to see Mount McKinley in the distance. The clouds never really clear enough for that to happen, but the ladies see a mountain that they think is Mount McKinley and are impressed by its size and beauty.
It turns out that what they're seeing is not the legendary mountain—it's just the base of a large and random mountain a lot closer to them that they think is beautiful. Walker ends her long story with this observation, so we know that it must be significant in some way to Irene and Anastasia's relationship.
While the women are not going to be BFFs any time soon, they definitely see each other more clearly after their convo at the bar. Anastasia is able to share all her bottled-up feelings about being biracial, and Irene has her eyes opened wide about her own behavior. In the end—and with the help of a bit of alcohol—the ladies come to appreciate each other as they always should have.
This little episode proves that the beautiful and powerful thing both of them have been searching for on the horizon has always been there right in front of them. It doesn't have to be perfect, and it doesn't have to look exactly like what they thought it would look like. While their relationship hasn't always been uplifting, it has always been there—like the random mountain—and something to cherish.