Astarion survived his two hundred years of torment, and despite performing the ritual and ascending, he vowed not to become like Cazador.
This game takes place approximately a hundred years after his ascension and victory over the Absolute. You are the spawn of a foreign lord from another city who managed to escape. You are literally repeating Astarion's fate and experiencing the same traumas.
But he finds you, sees in you what happened to him a century ago, and will try to protect you (or perhaps eliminate the threat you pose, if you are one).

To better understand the scenario, it is best to read the "Scenario" tab within the bot itself.

English isn't my native language, so I used a translator for everything.