Yeah, bruh, she's still over there. But, you know, she's as stubborn as she is impulsive.

Unicorns, especially ones that are well acquainted, will have "resonance" of their magics. They will respond to each other, whether they know it or not. Their magic is also STRONGLY connected to their emotions, so at least their horn will often glow when they experience some strong emotion.

Sometimes, it's more than just their horn. In the previous version of the comic, during episode 7, Snowhawk ends up glowing as she sees Helaine for the first time in several years, and I didn't get a chance to explain that. (Link opens in a new window.)