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Theoretically, yes, you can have four parallel stories. The relevant trope is called Four Lines, All Waiting. The most famous example of such storytelling that comes to mind is G.R.R. Martin's Song...
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Source: https://writers.stackexchange.com/a/40586 License name: CC BY-SA 3.0 License URL: https://creativecommons.org/licenses/by-sa/3.0/
#2: Initial revision
Theoretically, yes, you can have four parallel stories. The relevant trope is called [Four Lines, All Waiting](https://tvtropes.org/pmwiki/pmwiki.php/Main/FourLinesAllWaiting). The most famous example of such storytelling that comes to mind is G.R.R. Martin's _Song of Ice and Fire_. However, the downside of this approach is, as implied by the name, that at any given time you have multiple storylines "waiting". Readers are being jumped about different sub-stories, and have to wait a long time before they find out what happens next with each one. Employing this method right from the start, with characters who are not yet connected, can make it hard for readers to figure out what's going on, who the main character is, how they connect, why the jumping around. Challenging and confusing the reader before they are committed to the story and the characters might very well cause them to drop the book. You might remember that G.R.R. Martin tries to avoid this: the first few jumps are all within one locale (Winterfell), and between characters who have already been introduced (the Stark family). You, on the other hand, wish to jump between characters who appear at first not to be connected. An alternative approach could be to introduce the characters' backstory little by little - through what they tell of themselves and what others tell of them, after the MC has met them. Consider, for example, _The Lord of the Rings_: Aragorn has lots and lots of backstory. But first time we meet him, he is just 'Strider', some stranger the people of Bree treat with suspicion. He then tells us (by way of telling the hobbits) that he has some knowledge of the Nazgul, and experience in the Wild. It is not until the story reaches Rivendel that we learn who Aragorn really is: rightful heir to the throne of Gondor and Arnor, leader of the Dúnedain of the North, betrothed to Elrond's daughter Arwen. And even after, we continue to learn more about him: in Rohan, for example, we learn that he'd been there before, and spoke the language. This mode of storytelling would put the reader closer to the MC, "on the MC's shoulder", as it where. That is, the reader would learn about the other characters - who they are, what their stories are, together with the MC. It's not necessarily better - interesting effects can be created through the MC not knowing something the reader knows, but it is something to consider.