'Hmm? There's something leaking from him...' The brain thought as he 'looked' at Lucifer.
The brain focused on this something leaking from Lucifer better as he tried to close in on it with his senses.
Well, the only senses that the brain would have is...nothing. He could only feel around with his magic and try to make out what kind of object or living creature he is dealing with by using his brain and thinking faster than ever.
Of course, this is what the brain did as he focused on this...strange something that was leaking from Lucifer.
And what he could make out from this is...nothing.
Since the brain really could not see or feel, he does not know what to think if...he has not come across with it.