Ah. That I can explain. There are "bonds" between what they call monsters and witches here. It allows... a balance of magical energy between the two, for the lack of a better term. For that purpose, many witches and monsters choose to bond - either to an opposite or to another witch or monster.

[ She would explain more, but A2 seems bent on heading back out into the crowd. Saber starts and then follows after her. She's not really one to simply be shaken off. ]

You shouldn't simply wander off. I understand that this place is confusing and new, but there is the possibility that you will be brought here permanently.