@hunxi-after-hours asked for 水仙 recs, I was surprised by how few I've read, and now I'm thinking about what I classify as having 水仙 vibes and why they don't meet the criteria for being a 水仙 story.
Proposal: platonic ideal of 水仙文 is a character study that is also a romance about learning to love yourself.
马甲文 (subcategory: alternate identities have physical forms and some degree of independence, not necessarily completely 独立) deviate from this ideal in a few directions: usually more plot-driven than character-driven, the plot is not usually romance, the character study aspect is diluted by the 马甲 staying 'in character' instead of being like the main body. Also, aesthetically, they have different physical forms and there are often more than two of them.
Similarities, or the core of the wish-fulfillment thing that I look for when I read either of these: [love yourself]. To have someone who knows you and loves you and supports you absolutely, because they are you. To not have even the possibility of fearing that they will betray you or abandon you or misunderstand you, because humans may be selfish but even selfishness points towards this; there can be no more fundamental motive than wanting yourself to thrive. (And sometimes the main character has to grow into it, but that's just good contrast.)
Thought for consideration: there have certainly been love interests who have this kind of single-minded obsession with the main character, but the dynamic there feels very different to me.
Under the cut are some webnovels I've finished that match some of the above aspects.
Filtering works I've finished on 水仙 vibes that don't qualify as 水仙: (note: this is more analysis than recommendation. As context for recommendations, I warn that I am very tolerant of bad plot, slow pacing, brainless worldbuilding, and clumsy characterization, though not all at once. My Chinese is not the best, so I don't catch style very well. My only hard demands are that I can see that the author is trying to tell a story, and that the grammar is not unbearable. Nevertheless, I have finished these, so there is some filter.) These are all on 晋江.
《重生之出魔入佛》 by 柳明暗: almost 3 million characters long, very calmly paced. I wouldn't recommend reading this for 水仙 reasons, but the main character does split himself in three and they bicker frequently, for a definition of frequent relative to the story length. 魔, 佛, guy in the driver's seat. All of them are him, and consequently none of them are "good guys". Imagine trying to get out of doing chores when your opponents are also you, and you'll have the right idea.
《这个直播我承包了》 by 白昼粥白: shy, anxious high school girl gains confidence in herself and saves the world with the help of her imaginary friends/stuffed animals/character personas. Not a romance, no separate body interacting with MC, but pretty heavy on the [love yourself] theme. The dynamic is kind of like Calvin and Hobbes, if Calvin was a bullied teenager.
《全球升格》 by 子木桃: the 马甲 stay in character when they're independent, but they do like main body MC romantically. I find the jealous possessiveness obnoxious, but it isn't the main plot. There is unconditional support -- it is helpful, when you're trying to save the world, for the organization you're leading to exist only at your whim.
《全世界都以为我和我马甲是一对》 by 四海孤舟: I haven't finished reading this one, but the outside POV shipping is strong. The plot creates many coincidences and misunderstandings caused by trying to save the squishy main body. I don't remember how independent the 马甲 are, but it's classified as 无CP so I'm guessing the internal experience of romance is not strong in this one.
《大佬都是我马甲》 by 岁既晏兮: like above, the romance is mainly outside POV misunderstanding what motivation someone could have for doing so much for someone else. I don't remember what the main character or her 马甲 were thinking.
The author 施釉 has a category of finished works called 【完结1-我与我周旋久，宁作我】, of which I have read 《反派她每个马甲都是正道之光》 and 《如何扮演四个美强惨》: all the 马甲 really like the main body MC, so if you're here for cuddles and supporting the MC you'll get that, with romantic undertones. There is an attempt to blend the 马甲 being in character and being recognizably the MC at the same time. I have to say, though, that the author’s writing is hard to parse in a way I can't quite put my finger on; something about sentence structure that isn't grammatically correct? Confusing scene transitions? My fluctuating Chinese skills? More than one of the above? Also, the story logic isn't the best and it is a bit gratuitous with outside POV of the MC "suffering", but it's junk food that I really like the flavor of.
Concluding thoughts: common to all these is that the MC has a goal and the 马甲/other selves have no higher goal in life than helping them. 马甲 dilutes the 水仙 vibes because jackets are different characters and so less of the MC's self, but there's still the intimacy of knowing each other more perfectly than any two people ever can (since memory/ knowledge is often transferred). 马甲文的爽点 being the dramatic irony in outside POVs combines interestingly with 水仙 motivation of loving yourself.
There is a time and a place for stories where the main character goes through the character arc of "not wanting romance" (distinct from obliviousness, I have separate opinions on that) to "I accept and return your feelings", plus or minus working through some trauma, but sweet jiminy cricket aromanticism exists and is not a character flaw that has to be developed away to have a happy ending. Flip side, let characters be normal about unrequited love for once, I'm begging you.
This post has been brought to you by certain webnovels that shall remain unnamed.
