On the subject everyone was discussing earlier about how to write a Psychopath in a way that can make them sympathetic, it's really not something that works unless you more or less don't play them completely straight. By definition these people are not supposed to seem "human" (it's like their soul was taken from them, or at least locked away inside) or even appear afflicted by their condition, which is why so many of them usually end up falling under the trope of "Complete Monster". However, if you really want to find a way to portray something akin to the "Heroic Sociopath" trope and do it sympathetically (I've been considering an example of this for my project that simply isn't official yet), I suggest you consider watching an anime called Naoki Urasawa's Monster. There's a particular character in it (I won't name them, for the sake of spoilers, so PM me if you want the name) who does a really convincing job portraying a person who has lost the ability to feel proper human emotions yet still manages to be sympathetic because of how they are aware of the fact and bothered by it. I'd highly recommend this show to people regardless, but it's probably the best example I've seen of this concept done well.

As the original poster said, I too wonder if my characters are written like normal people or like myself, but I'm fairly good at writing the perspective of a more normal (whatever "normal" means; mostly another word to describe "majority") person, and many of my characters are meant to carry some facet of myself anyway, so this isn't something I'm too worried about.

Alongside the whole research recommendation (which I've also pointed out on my end), [@ELGainsborough] made a good point about taking into account the time period. For those who saw my last post, they should understand that I have a personal understanding of how relevant this fact is.

As I mentioned earlier, I've been diagnosed with Asperger's and while I was incorrectly labelled with many different disorders throughout my life it is the only one that is still considered official. The time period I was born in is important to that. Doctors have more understanding of Asperger's now, and even 5-10 years ago, than they did when I was a child, and schools are also more accepting and actually attempt to find ways to assist people with the disorder, while back when I was younger schools pretty much did nothing about it. I was basically blackmailed by my high school principle to leave so they didn't have to pay to help me, because getting assistance was rather difficult back then. The lack of understanding from doctors, counsellors, family, peers, schools, and even just society in general, resulted in them taking numerous actions that severely ruined a large portion of my life and still carry weight on it now.

I don't know how old the original poster of this topic is, but, at least in my personal experience, Asperger's is definitely something that would bring suffering to your life if you were a child with it in my time, not because there was inherently anything wrong with you, but because of how other people would react to you. I won't go into a big explanation about the social problems it caused, but I'll at least mention medications. I spent a good majority of my younger years on a drug called Ritalin (among other things), and if you know what that is in any detail then you should know it severely screws with people's heads and their hormones. They usually give it to people with ADD, which I was misdiagnosed with, and even with them it's not always a good option, but for people who don't actually have ADD the results can actually be devastating. Asperger's is generally something that should be cultivated and worked with, not medicated. Side effects are also a very important factor to consider, since medications always carry them and the ones for mental disorders often carry invasive or damaging consequences regardless of how much professionals will tell you otherwise.

This sort of ignorance in the medical field of various time periods, even the time of my childhood, applies to disorders outside of strictly mental ones too. For example, I quite likely suffer from a nasty piece of work called fibromyalgia, a condition which can only be reliably treated or even helped with at all when you're young, but when I was young doctors didn't even believe it existed, and this fact has had an unprecedented impact on the rest of my life just like how they handled Asperger's.

Back on topic, however, another example of how timeline effects things like this is the way several mental disorders would have been believed to be the result of possession in older days, rather than a mental disorder. This is why it's actually common now for people who would be considered exorcists to consult a psychologist about a patient and have them do an examination on them first, before the exorcist does anything, in order to confirm the ailments can't be explained through non-paranormal means first. Due to that, writing a character with a mental disorder in a historical piece of writing can also be trickier than writing one set in our time period. On a similar note, it can be difficult to write these disorders in a futuristic setting since there is no way to know how they will be handled by that society, and this obviously applies to any fictional setting as well unless the author/GM takes the time to explain it.

Like they just said in their post, details are essential, so researching is very important, not only into the conditions but also the treatments. This is why in my previous post I recommended that you try to get opinions from people who actually suffer from these ailments, or read books that were penned by someone who was writing from personal experience, since they will provide the most wisdom on the subject. No amount of professional education on a mental disorder will actually help you understand it on a personal level unless you're very good at getting into other people's heads, and even then without empathy it will be difficult. That's why it's a good idea to learn from people who actually go through it. Of course, like I also mentioned before, people with certain disorders (Sociopaths, Psychopaths, and Narcissists, for example) are usually consummate liars, so this suggested probably won't be helpful with understand them since they are more likely to give a testimony that is self-serving in some way.

While a psychology degree can help a person learn about psychology on paper, a deeper and more personal understanding of human psychology will be far more helpful. Insight into psychology is where I specialize in this field, rather than the "on paper" stuff. That's one of the reasons I'm able to read and understand and empathize with others in ways that a medical profession is unable to, and it subsequently aids me significantly with writing characters.

Definitely in agreement with [@Dark Wind] as well. You never want to let other people's opinions dictate what you do or don't pursue as the topic of your writing. I stopped caring what other people thought about me a long time ago, and it's had an exceptionally positive effect on my work and what I can take and give from it.