You play Adastra first (with the human and Amicus), then Interea (a spin-off, happening before the end of Adastra, with the human and Amicus), then you play Khemia, which is half a sequel, and half a spin-off, happening two years after the events of Adastra. In Khemia, you don't play as the human but as a Wolf named Scipio (but you meet again almost all the characters from Adastra)