Gemini is the fusion of Reylynn and Senri. She's been with us since the Wedding. Being a combination of these two souls, she is reliable but also reckless and unpredictable, but still someone you want on your side.
From what we've seen, Gemini feels like we've been with her since the beginning of our journey, as she behaves mostly as a more brave Reylynn, as if Senri is improving the other side.
