The truth behind Agrippa (and Alexander [spoilers]).

[Smithens]

Good points, Tintin. But about his attitude; one might think that his personality (based on external observation) is unbalanced for human standards. The way he goes about harming Daniel and maliciously torturing people is nonchalant, cold, and calculated. But Alexander is hardly human. He comes from a higher society of beings, and his disregard for human life can easily be explained by this.

Alexander may or may not be sadistic, but he is definitely an "ends justify the means" sort of fellow, which can be considered pretty "evil" no matter how noble his intentions are.

Despite what I just said, I believe that he intends to return to his world for noble intentions, not to wreck havoc. It's only been implied that he was forcefully cast out of his old world somehow, we don't know the reasons or whether or not it was an accident. I think that the old man just wants to get back to his wife. He mentions in one of the notes that he wishes to be reunited with his "love."

E: Also, since we seem to be discussing Alexander too, I changed the topic title