The line between speculation and fact is somewhat blurry in this article, but he does give examples of a dream characters who have knowledge that the dreamers coudn't possibly have had. So we can exclude the possibility that dream characters are part of the dreamers' personalities.

As a Christian, I have no problem accepting the alternative that these dream characters could be independent minds of spirit beings.

But is there any third alternative, or just the two options that the characters are part of the dreamer's psyche, or disembodied spirit beings?

Do you guys have lucid dreams? (I don't, except for maybe two or three occasions in my lifetime.) If so, do you interact with dream characters? Who do you think they are?