Mine usually sit quite stiff for the first minute or so on my knee, looking round and sniffing the air. After that, they put their head down, and eventually stretch out and "pancake". You can tell how relaxed they are, by the feel of their body when you are stroking them, they eventually feel like they have no bones! Luna stays quiet throughout, but Ginny will make little chattering noises occasionally. I must admit I am never quite sure about the noises, but the body language is very clear. If I stop stroking them, they lift their head up and look round, when I start stroking again, they lie back down!