User blog comment:Derax-Pagani/Chapter 502 Review/@comment-24546844-20160917201439/@comment-7418318-20160917203932

I don't think Dimaria intends to torture Lucy "directly", juding by her putting the sword to Natsu's neck.

She holds Lucy responsible for "killing" Brandish and thus taking away a person that Dimaria loved, so I think she intends to do the same to Lucy by either torturing or killing Natsu before her eyes, once Lucy wakes up again.