Isekai'd as a side character

Venianne was living her life peacefully until she was reincarnated in her friend's novel as a supporting character. Fortunately, she knew the story well, but her destiny did not seem all mapped out as she hoped.
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○ I know I said no long term past ones, but by the end of chapter 16 it goes to the present, and it looks like it’s gonna be a long series

I've been reincarnated as the younger sister of my favorite novel’s male lead and am destined to be poisoned by her step-mother at the age of seventeen.
My brother is on an adventure with the heroine so I have to survive by myself. Should we start with survival plans?
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○ : child abuse

In the story, Duke Gerald is hated due to his cruelty, but as Ann dives deeper into the story, she wonders if his demise could’ve been avoided.
She shakes off the thought, knowing she can't change the story’s ending. That is until she is transported into the novel.
Ann is informed that she has 90 days to change the duke’s fate, and if she fails, she will die.
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○ character likely dies in OG but not confirmed

On a normal day like any other, Duchess Juliana Auburn woke up from a dream. No, rather, it is I, Isian, who remembered my past life.
Juliana Auburn, according to a spoiler comment that I read, will be killed at the start of the novel.
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○ promo
○ She calls herself a villainess but just in the sense that she is a bad person

She possessed Charlotte Rania, an extra that was not even mentioned in the original book. She had thought that the bloody social world and politics were stories from another world. Until she accidentally met her brother-in-law and saved him. But this little kid started swearing that he wouldn't go home. The male protagonist, Carlyle Heinst, who has to marry the original female lead by contract, offers Charlotte her contract marriage.
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I am the villainess in a harem novel. My role as "Erika" is to be an evil ex-girlfriend. I don't want to be a dumb villainess, so I broke up with the male-lead first... But after 3 years, Leo came back to me.
"I can't live without you. I still like you..."
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○ Says she's a villaines but sounds like she was a minor one and not the actual antagonist

Lizia is reincarnated into an otome game world as a mob character. She decides to live with two lives worth of filial piety, however, she has been betrothed to Bernhardt, the last villain in the prince's route. This is the struggle of Lizia as she tries for a peaceful life.
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Hayoon Lee dies and is reincarnated as a character in a teens’ love novel she read before her death. She is Nina Cage, the maid of the female lead, who is fated to die as a plot point to get the leads together.
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○ Including death tag b/c though her actions that lead to her death can be avoided, Nina’s in an inherently dangerous situation
○ She and ML have a four year age gap but nothing happens until after a five year timeskip

When Meia realizes she’s woken up in the story “The Flower of Shakir,” she has no intention of becoming the side character who is sacrificed just for the sake of the male protagonist. But during her grand escape, Meia runs into Duke Rakha Aintia, the story’s villain, and his two younger siblings. In an unexpected turn of events, Meia is hired as the twins’ sitter, but she also happens to attract the duke’s attention.
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○ Sounds like OG was forced

The possession that happens to others befell on me too. I’m pretty sure that I’m a supporting character… But what on earth is this novel? On top of being a widow with stepdaughters of my age, I’m living a cursed life in which I transform into a black swan every night because of black magic! I need to suppress my tears and change my fate.
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○ promo
○ little info thus far, as just the promo has been released