I get that you don't headcanon Jekyll/hyde as a plurality but is there any evidence that he isn't plural?
He doesn't meet the criteria for diagnosed DID at all in that Jekyll is completely aware of Hyde's actions and Hyde still writes in Jekyll's handwriting and keeps some of Jekyll's habits.
Jekyll refers to himself in first person when he describes his transformation and how he's not disgusted by it and when he transforms into Hyde spontaneously he looks down and is surprised to see his hands have changed.
When he does separate himself from Hyde it's always a matter of guilt or unwillingness to admit that he could be that depraved. It also feels very strongly like "Sober me isn't responsible for drunk me's actions," which is a thing people do, especially people who have substance abuse issues and don't want to admit that once their inhibitions are compromised they do things that they're deeply regretful or ashamed off. Hyde isn't a different person he's Jekyll with no impulse control and compromised judgement. That's not to say Jekyll couldn't push himself to create a deeper separation as he spirals into psychosis due to stress and probably a significant amount of sleep deprivation. But it's not Jekyll/Hyde's default state.
Stevenson himself would also dispel the notions of DID in letters he wrote as a response to a fan.
Also, in terms of writing Jekyll/Hyde as being a plurality you significantly risk making that depiction ablest because it plays into the "good personality/evil personality" dynamic that was popularized as a film cliche. Unless you have a certain skill level in character writing there is almost no way to write the two as being separate entities without making Jekyll the "good" half and Hyde the "bad" half because the story is about that duality and a man's capacity for good and evil. Making Jekyll the "good" half and Hyde the "evil" half is also reductive to the character as it removes his responsibility for his own actions and his agency in his own story. Jekyll becomes Hyde's victim rather than a man who represses himself to a breaking point and then loses control to his own inner demon (metaphorical not literal).
turnnoffyourmind
discoholicmusic
baratheonpilled
kianamaiart
dailybridgerton
prguitarman
pixelskylines
origamiaround
