Why can NiGHTS even Dualize? Like all Nightmaren, it was created by Wizeman... who, if I remember my series plot correctly, despises Visitors, and wants to make the Night Dimension into an endless nightmare where they will no longer be welcome. So... why would he even create a minion with the power to fuse with Visitors?
'Could be general dream physics. Everything might be able to, given realisation and willingness in both parties. S'my personal explanation anyway.
NiGHTS possibly could have developed the power on hir own after s/he left Wizeman's side. After all, what better way to piss off one's creator and former master than to team up with the very beings you know he despises in order to beat him?
Perhaps dualizing was originally used without consent to possess visitors, but after NiGHTS left Wizeman, NiGHTS decided never to possess visitors using dualizing again.
There's several things that bug me about the comic, but the whole "NiGHTS and Elliot switches body" thing in #2 takes the cake. Ignoring that Dualizing doesn't work that way, the reason they do it is because they need to find Claris while Elliot takes care of the bad guys in the Dream World. Fine, except at the end of #1 Claris had already been found by NiGHTS. There was never any reason given why NiGHTS couldn't just un-Dualize to explain what was going on! Aside from "to let her carry the Idiot Ball", that is. Not to mention how NiGHTS seemly didn't have any plan on how to find her.
Why didn't Reala just take the visitors ideya? He grabbed them several times and did no more than teleport them to some random place.
The Idiot Ball is obviously in play to a degree later in JoD's story. It made sense the first couple times, since Nightmarens explicitly cannot touch Red Ideya if a Visitor is in possession of it, regardless of level. But who's to say he couldn't just strip Will and Helen of the others? It's not like it would break the rules of the 'verse, anyway.