No, what's convenient is post-hypnotic suggestion. If they command something of you while you're looking at them, and you look away--you'll be doing what they say, whether you like it or not.

Really, their biology isn't very interesting--that's the bit that makes you forget once you turn away. It's almost the same as another creature, a Weeping Angel. ... must've evolved differently.

[ sorry, bit of a tangent, and he doesn't look particularly happy. he looks quite old, and tired, and he isn't perking up. ]

It's a very good thing that Asgard doesn't seem to attract any of them.