Crothian has it pretty much right. This is from the shooting script for Blood Ties, in Season 5.
Dawn is subtly working Glory for information about the Key, trying to find out everything she can about herself.
DAWN
So this Key thing. It's been around for
a long time.
GLORY
Not as long as me, but yeah. Just this
side of forever.
Dawn absorbs that. Forever?
DAWN
Is it… evil?
GLORY
Totally. Well, no, not really.
(shrugs)
I guess it depends on your point
of view.
Glory twitches just for a second, like she's working a kink out of her neck.
DAWN
What's it for? I mean if it's a Key,
there's gotta be a lock, right?
GLORY
Yes! We have a winner!
DAWN
So, what does it open?
Glory starts to answer, then suddenly stops, her eyes narrowing.