[Spoilers] Amnesia Plot

[thePyro13]

I never read anything that said Alex had to come from our world. He was banished from the other world, and has been trying to get back.

Those memory capsules mention his love, which he wishes to be reunited with(this could be referring to a woman, or just simply his true home).

He was defiantly extending his life somehow. One of the flashbacks or notes details how he does the same to Agrippa.

I'm running under the suspicion that the darkness isn't an entity of itself but really a personification of the person who activated the orb. Agrippa's student was said to be a great man, and he remains on the other side. I assume this is because he is capable of wielding the orbs properly.