Beatrice came to the church searching refuge from an abusive aaranged marriage, which the Church offered gladly. The longer Beatrice stayed, the easier it is to see that Beatrice was led to serve the Church by Elios, when she fits in casually with the other Chosens.
Beatrice is seen as a older sister figure with her gentle and kind nature. Especially, with the way she cares for her roommates who happened to be younger than her.