Various mental health conditions have existed and were at times recorded. Names and classifications of mental illnesses changed over time and it is a tricky field to navigate, especially for someone who is interested in the history of medicine. But that's a whole nother discussion.
As far as I remember the English term OCD (obsessive-compulsive) is a translation of the German word Zwangsvorstellung ('obsession') and was first mentioned in the 19th century. Before that, it didn't have a specific name. If memory serves me in medieval Europe people looked at what we would now call OCD as possession by the Devil?
I don't want to intrude on anyone's creative decisions about characters and how they want to develop them... However, I would like to stress 2 things: firstly, although the popular perception of OCD is a person who doesn't like a mess and is constantly tidying and cleaning - that's not what OCD really is. It's not about habits such as cleaning, tidying or hand washing. While most people have obsessive thoughts and/or compulsive behaviours at some point in their life it doesn't mean that they have OCD. For more information please check out the International OCD Foundation.
Once again, let me be perfectly clear on why I stressed this and provided the link above: I do not wish to intrude on anyone's creative decisions about their characters and how they want to portray and develop them. I simply wanted to stress that OCD is a serious mental condition, not a quirky habit. I know fellow historians who have been hospitalised because their OCD got out of control and I'm very, very careful how I approach this or any other neurodiverse disorder. So please consider what I said as me sharing information and pointing some things out
That being said, I really enjoy reading when people do decide to write about these themes and seeing how they tackle them.
P.S. @Lailyn @Winddancer my post in the Tower Guard is finally up. So sorry it took me so long, I just couldn't have the time to finish what I started. And sorry Lail I'm afraid that Nessa will be on Hathaldir's back until he solves Thea's case.