Foreshadowing Ideas

• Character themes/motifs. I’ve heard of one writer who tries to give each character their own theme for similes, metaphors, descriptions, etc so there’s like a theme to the way they’re portrayed. You could use that to foreshadow notable secrets about the character that will later be revealed, or if at any point they’re disguised then you can use that to tip off the reader that they have the same motifs and so might be related/the same person

• Tiny details hidden in lists. Say the MC was trying to work out the identity of a bad guy, who we know was wearing a red shirt on the day of a big bad event. A few chapters later, MC is checking around their best friend’s room to find them, with the place its usual mess with discarded takeaway boxes, the bed unmade, a red shirt left on the floor that could use a good sweep. The red shirt might not click with all the readers, but those who register it upon their first read will eat it up

• Inconsistent behavioural patterns. Once we have a good idea of what a character is like, having them act out of character can set off alarm bells and make us question what’s occurred to make them act this way. Let the other characters register it too, if it’s reasonable that they would, but let them ultimately brush it off quite quickly to keep it subtle. Or just call it right out, whichever you prefer

• Unreliable narrators. Let one character say one thing and a second character say another, even if they both ultimately agree on the same thing but get one or two small details wrong. Ideally do this two or three times in order for the reader to know it’s not just a mistake in the plot but an intentional inconsistency, but even if it’s only done once and it’s taken as a mistake it’ll still slot together like puzzle pieces in the end and they’ll be kicking themself for dismissing it

• In-universe red herrings. If you’re going to add red herrings as foreshadowing, it’s helpful if the red herring aligns with the intentions of someone person aware of the upcoming plot twist who’s trying to control the narrative. Say the plot twist was the reveal of a mysterious character’s identity to be the best friend of the MC, the best friend might have deliberately thrown the MC off their scent by planting suspicions in the MC’s mind that a different character was the mysterious character’s identity all along. This is less about foreshadowing the actual reveal, of course, but rereads will be a punch to the gut when everyone realises that all this misinformation and red herring business came from someone trying to cover their own ass rather than coming from misunderstandings or multiple other random sources