Thanks! They're actually not all that afraid of people, which is why they decided not to return them.
They do hide for a while (we have a tree with a cubby hole and several boxes for them to hide in). But if after they decide you're not trying to trap them, they come out and nudge your hand for petting; Muninn is a bit shyer, but she follows her brother's lead so when he came out purring she just followed him around.
Hades is sitting by my foot now, probably because he already knows the bag on my desk has yummy treats.