I brought this over from yesterday's thread, I think it's a pretty important point:

DrinktheKoolAid wrote:
there were spoilers a long time ago that Nik was going dark


Didn't the spoiler suggest he may have already been?
dotsgirl wrote:

It seems like it is going to be more and more obvious to the viewers as we move forward, don't you think?   He has the polite exterior but underneath it all he is a Cassadine. 

Why would Nik allow Hells to live w/him after all she has done?  He knows how dangerous she is to Liz.  Something is fishy....

So, to add my 2 cents...
I find it very odd that Nik would go after Liz to begin with, the Nik we know from before that is.  For him to all of a sudden become obsessed with his brother's ex-wife/current fiance?  Weird.  That's where it all started, IMO.  So I have to think that he's been dark since then, he's just been covering.  And dotsgirl makes a great point about him allowing Hells to live with him.  Good Nik wanted absolutely nothing to do with her.  He didn't even want to see her, let alone have her live with him and his son.  Wasn't he hellbent on keeping her away from Spencer?  So many questions...