Although, ideally, you should stick to just one perspective (eg: first-person or third-person) in your story, I’ve read a few modern novels over the past year or so that combine both perspectives in various ways. This is one of those things that is tricky to get right, but can work really well when it is handled properly.
In short, the main thing to remember is that you should clearly signpost the perspective changes. If you are jumping from one perspective to the other, then the reader needs to be able to understand and adapt to this quickly, so that it doesn’t become too confusing. One of the best ways to do this is to use italic text for one of the perspectives and normal text for the other.
For example, both Tess Gerritsen’s 2002 detective thriller novel “The Apprentice” and Dana Fredsti’s 2012 zombie thriller novel “Plague Town” use a variant of this technique, whilst also setting the two types of narration apart via slight changes in the narrative voice too. This makes the jump from one type of narration to the other feel a lot less jarring.
On a side-note, one interesting variant of this that I’ve seen in at least a couple of thriller and/or horror novels is to include short italicised first-person asides (typically no longer than a sentence or two) in the middle of a passage of third-person narration. Since these are fairly brief and are often used for comedic or dramatic effect, they can actually work quite well.
So, italic text is a great way of signposting changes in perspective since it is immediately visible to the reader and allows them to clearly tell which type of narration to expect.
If you don’t want to use italics, then make sure that each chapter of your story only uses one perspective. Not only does a chapter change get the reader ready for something different (so, the perspective change is a bit less jarring), but it also means that the reader has a bit more time to get used to a particular perspective.
You can also use other forms of signposting too – such as in Tade Thompson’s 2019 sci-fi novel “The Rosewater Insurrection“, where each chapter heading contains the name of the character it is focusing on. This means that you’ll soon easily be able to tell which chapters are in first or third person perspective based on which character name appears. Since two characters consistently use first-person narration, and the other characters’ chapters usually use third-person narration, then this is fairly easy to follow after a while.
In addition to all of this, you also need to have a good reason for including perspective changes. For example, Tess Gerritsen’s “The Apprentice” includes first-person perspective segments because they give the reader a chilling glimpse into the twisted mind of one of the serial killers that the detective is trying to catch, adding extra suspense and horror to the story. Likewise, the third-person segments in Dana Fredsti’s “Plague Town” lend an extra sense of size and scale to the novel’s zombie apocalypse. In both of these novels, the perspective changes serve a valid practical purpose that adds something to the story and allow the author to use the best elements of both perspectives.
In Tade Thompson’s “The Rosewater Insurrection”, the reasons for the multiple perspectives are a bit more subtle, but they still have a practical purpose. The first-person narration in the opening chapter is a good way to maintain consistency with the previous novel in the series (which only uses first-person perspective), which makes the transition between the two novels a little bit more seamless. Likewise, one of the extended first-person segments later in the novel allows for some character-based stuff that works slightly better in first-person perspective.
So, in conclusion, if you’re going to use both first and third person narration in your story, then your changes should not only be signposted in a simple and consistent way, but they should also be there for a very good reason. In other words, if your story still “works” with just one perspective, then just use one.
Anyway, I hope that this was useful 🙂