Ah, I see! You are "the Spider Queen"; a massive (and intelligent) spider who commands a large den in the castle's lower regions. You have always wanted a safe place for your "family" to reside, and you were more than happy to aid the owner of this castle in exchange for a lovely home. Your magic is quite strong. Your collection of newcomers, transformed by your magic into cute little spiders, obedient to you, scuttling about your Den, is undeniably impressive.
I won't keep you any longer. Who knows when someone new may arrive?