I think Dana might have Stockholm syndrome.
(I know Stockholm syndrome is not technically a mental illness or psychological disability but I'll get to that, just needed that clickbait title babbbeeeeee)
Stockholm syndrome is characterized by a few different ideas but the basic concept is that of a hostage developing positive feelings towards a captor. Although Rufus does not fit the traditional role of a captor, nor Dana that of a hostage, I believe these two tags are still very applicable for the relationship between the two characters. Rufus has the ability to call Dana back into the past where she becomes trapped in a place she does not want to be for up to several months. Dana is not being kept for a ransom, instead she is in a worse position as a slave. The main deviation from the captor/hostage labels lie with Rufus' intention (or rather lack thereof). In an actual hostage situation it is impossible for the captor to accidentally take someone hostage. The captor traditionally has a certain amount of control. Instead Dana gets called back without Rufus actually meaning to. Dana cannot be ransomed off to her family since Kevin is in the future for most of the book, however she is a hostage against herself. Anything that goes wrong directly hurts her and her getting sold would only affect her.
Dana (for the most part) likes Rufus. She believes they have something special going between them despite there never being any verbal confirmation. She saves his life time and time again and always gives him the benefit of the doubt. She has a very complex relationship with Rufus because they are however distantly related (great-great-great-great-great whatever at this point the word great has lost all meaning grandfather), however if she truly despised him then her attitude would have been extremely different, only doing the bare minimum to ensure his survival and get him and Alice together. Instead she becomes emotionally involved, even sympathizing with him despite the harm that has come onto her which is all indirectly his fault. Even in the end when Rufus is attempting to rape Dana, she thinks about just letting it happen, thinking it might not be that bad. The amount of effort it takes to convince herself to actually fight back shows that there is something going on in Dana's head. This is more than just a complex relationship.
Why is this not quite Stockholm syndrome?
They are related. (I think the relationship is distant enough that this doesn't matter all that much, plus Rufus doesn't know. I'm not any sort of expert though so idk ¯\_(ツ)_/¯ )
However, at its core, Stockholm syndrome is about the the mindset an abused person feels towards a captor or abuser. Dana demonstrates two of the main three parts of Stockholm syndrome: positive feelings towards a captor/abuser and a sympathy for their beliefs (the third is a negative feeling towards police or other authority figures but it doesn't quite seem applicable in this situation). Stockholm syndrome is a coping mechanism, it helps preserve the safety of an affected individual. I think Dana shares some traits with traits of Stockholm syndrome but I cannot say with 100% certainty that she has Stockholm syndrome due to the complexity of their relationship. What do you think?
I think all clickbait should have some tiny disappointing kernel of justification so here it is: Dana 100%, irrefutably has PTSD at the end of the novel. This is categorized as a psychological disorder meaning technically my title is accurate despite not being applicable to the majority of this post's content.