Starting off with a disclaimer that I do not have D.I.D nor am I an expert on the subject. I know only people with first hand experience of having the disorder and specialists who treat the disorder are going to have way more experience that me.  So what I'll be explaining is just from a layman's perspective. 

I started off learning about D.I.D through Kill me, heal me and then wanted to know more. So for a few years I have been watching videos of people who talk about their D.I.D in a way to try to understand it better.

"According to the Diagnostic and Statistical Manual of Mental Disorders, 5th edition, text revision (DSM-5-TR), there are five types of dissociative disorders: 

  • dissociative identity disorder (DID)
  • depersonalization/derealization disorder
  • dissociative amnesia
  • unspecified dissociative disorder
  • other specified dissociative disorder" (psychcentral.com)

I'm not too knowledgeable with the others, so I'll just focus on D.I.D here.  So here goes. 

1. D.I.D is a trauma based disorder that occurs when in early childhood, a child has experienced trauma that has affected them to such an extent that they are unable to cope with what has happened to them or possibly what they were forced to witness. According to the theory of structural dissociation it "works off of the assumption that no one is born with an integrated personality. Instead, infants operate based off of a loose collection of different ego states that handle their different needs- feeding, attachment to a caregiver, exploring the world around them. Over time, these ego states naturally integrate into one coherent and cohesive personality usually by the ages of 6 or 9" (did-research.org). 

2. When a child develops D.I.D, those identity states start operating on their own as alters or altered states of identity.  Each identity state will have its own memories, likes/dislikes and personality. Alters are not the same as someone who actively decides to be someone else or be a different personality state. We all have those personality states - at home, at work, with our friends but they're still us. I know the series was trying to use the amnesia barriers as a way to show D.I.D but all they were doing is making Eunho look like she was playing pretend (intentionally) before she forgot about it. The development of alters all depends on how the individual's brains works and how it copes with trauma. Two children might have the same trauma experience but both might not experience D.I.D or one of them  might. It all depends on the individual.

3. Alters can communicate with each other both in the real world and in the subsconscious but it's not always straightforward. We do have "Haeri" writing letters to Eunho (as the show is somehow depicting amnesia barriers between personality states) but there is no subconscious communication between them. I have read that it might not always be easy for alters to communicate with each other. Some might just want to be left alone. Some might be more active and want to stay closer to the conscious mind. Subconsciously they can communicate with each other inner world or consciously through co-fronting or being co-conscious with each other. I'll explain what they are in a bit. 

4. Inner world is basically a headspace that the brain creates for the alters to interact with each other. It is unique to systems who have inner worlds as one can be a room, another a house, a city, planets, anything that the mind decides to create. Sometimes a system might identify it as a lucid dream. However it is important to note that not all systems i.e. system of alters would have an inner world. According to powertotheplurals "Innerworlds are a therapeutic tool. It is widely used for many therapies and reasons, one of them being Dissociative Identity Disorder. Some people with DID (or OSDD) grew up with their innerworld. Others want to create one after a diagnosis or when they read about innerworlds."

5. Before I go into writing about co-conscious and co-fronting I need to explaining what switching is. Switching is what happens when alters switch places from the conscious mind to the real world. The alter in the real world would be known to be "fronting". Sometimes switching can be conscious and intentional while other times it can be out of the blue. Switching can happen due to both positive and negative triggers. Eg a positive trigger could be an alter's favourite song. A negative trigger could be dealing witha  bully. Switching can be covert and unnoticeable to others around them. But sometimes it can be overt or have a longer and uncomfortable dissociation process. Contrary to what certain dramas like to portray (and this isn't about Dear Hyeri btw) switching is not someone going back and forth talking to themselves like a crazy person. @ Dramas who do that - enough already. We do see Eunho and Haeri switch via sleep and waking up and I can't say whether or not that a way switches happen irl. Only systems would know. However the series is feeding into inaccuracies by only showing sleep and waking up on a schedule as the only way to depict how switching will occur. 

6. Since I mentioned fronting, it's time to mention co-fronting and co-conscious.  Co-fronting is when at least 2 alters are in control of the body. In this case, their identities will temporarily blend together as they will be able to coordinate the body's moments. However co-conscious means that the alters are in the conscious mind but are not the ones fronting. It is easier for those in the conscious mind to communicate with each other and with those fronting as well. 

7. Alters can have various roles within the systems. There can be trauma/memory holders, protectors, gatekeepers, caretakers, persecutors etc. I know persecutor alters can be mistaken for "evil" or "bad " when it's their way of keeping the system under control so they wouldn't go through more abuse from the outside world. It's a complex situation that does need healing on all sides. Also if DID was being portrayed correctly, Haeri would be known as a type of Introject alter as she is based on someone Eunho knew irl.

8. Within the series, Eunho's psychiatrist has spoken about merging while Haeri expressed her fears as to what would happen to her once she and Eunho "meet" or something like that. So let's pretend for a bit that they're depicting D.I.D correctly. Haeri will not disappear or die.  However the psychiatrist using only merging as the solution is not the way to go. The system can decide on functional multiplicity, integration or final fusion. Functional multiplicity means all within the system working together as a team, integration is about lowering of amnesia barriers between or among alters but still having separate identities while fusion is a more complete lowering of barriers between or among alters where they gradually fuse into one identity. 

9. System Accountability - this is basically all alters understanding that their actions can affect everyone in the system and with that sense of accountability they can be more responsible in how they act. Does that mean every alter is going to be picture perfect good? It doesn't. Everyone has flaws, everyone makes mistakes and if something happens that hurts another person, system or not, owning up to it is another way of taking responsibility while making sure it will not happen again.

10. One more thing to add is that, even if a child develops D.I.D they may or may not be aware of the alters existence. Sometimes alters might not realize there are others around. I guess depending on situations and people realizing certain things about their lives then they can be something unusual is going on with them but they don't understand what it is exactly. They might suspect some form of dissociation, however it is always best to talk to a professional who specializes in these cases in order to know what the official diagnosis for the individual would be. Plus even though alters start to develop in early childhood because the brain has already been conditioned in that way, it is possible for new alters to form or for alters to have their own alters as well.

There is a lot more to discuss in relation to D.I.D but right it is almost 1 am and my brain is fried. So please forgive me if I made any mistakes along the way concerning D.I.D and what it's about. I hope this will help people understand a bit more about the condition.