When your writing a book and you want to give insights and thoughts of multiple characters as the narrator, how would you do that? For example I want to switch between my main characters, a brother and a sister and have the two of them both be narrators throughout the book.
It's hard to switch narrators seamlessly, so it's best you tell the reader it's a new POV by a scene break or a completely new chapter (I did this for one my projects). Depending on the type of POV, also make sure that they have distinctive voices. I hope that helped~
Have a read of some of George R. R. Martin's A Song of Fire and Ice series. He switches POV character every chapter, and yet manages to keep it seamless, fluid and have strong and fleshed-out characters. Part of his technique is to head each chapter with the name of its POV character.
I'll second this. A Song of Fire and Ice changes POV characters very effectively. He takes on an absolutely huge cast of characters too over the course of his series and I find his writing style extremely easy to follow and well narrated. To the OP you should do some research on using different POVs in novels if you haven't already. There is lots of information out there on how to execute it well. Showing you how to give each character their own different narration style. One example I like to refer back to is thinking of them walking down the same busy street. Imagine your female character is an artist. You male character might be a chef. Your female character might notice a lot of the culture and be extremely attentive to the colours in the street and the small details in the layout. Seeing beauty in almost everything. The male character at the same time would be describing the smells etc. Obviously the characters would be more complex than that, but that's the general idea of it.
Use an omniscient point of view... ? Switching scenes or chapters is the standard for multiple first-person views. Otherwise, it gets confusing. However, a multiple-first-person, restricted point of view might be interesting if you could manage to pile it all the POVs on top of each other. I'd like to read something like that, purely for academic reasons. I wouldn't want to be assaulted with that throughout an entire novel, though. Instead, giving me breathing room and a chance for the character's image to crystallize in my mind before being forced to assimilate another one is much easier on the brain. And, so it is with other readers. There have been some interesting things done with POV. One that comes to mind is a book written not too long ago that simply requires the reader to flip it over and start reading from the last page, backwards to the front. In other words, odd numbered pages pages read from one point of view, even numbered and reversed pages read from another.
In my main project right now I have multiple narrators. I give each narrator a different chapter and make it obvious that the POV has changed by naming or describing the character at the start if the chapter.
I agree with this as well. Also try reading the Wheel of Time series by Robert Jordan. It also roughly follows the character per chapter but changes POV within the chapter now and then, but it is always clear when he does so.
I agree that something important to do is give your characters distinct voices, make the feel of each of their chapters different. Since you're only switching between two characters this won't be too difficult if you can get in the groove of each of them easily, but if you add more characters I would consider moving it to third person. My story has ten different characters where each one is centered on in a chapter. I originally had it first person because I liked how intimate it is with the reader, but I found that it was much better to move it to third person so the reader isn't getting too confused from the constant change of viewpoint. With the chapters still focused on a specific person, this eased off the worry of sounding different each chapter. I could keep one style of writing and the feel would still be different since the characters all talked differently and used different words. I say go for it if you make it in first person, it should turn out quite interesting. A book to also consider is Malorie Blackman's Noughts & Crosses. That did a really good job in my opinion, especially with male and female characters. James Patterson's Maximum Ride series is great as well if you want to incorporate parts centered on other characters.
I think its definitely possible and happens a lot, you just need to really make sure to let the reader know when you've switched POVs. Like everyone is saying, George RR Martin does it well. An example of how not to do it, and I might be killed for saying it, is in Stephen King's "The Stand". He switches back and forth between POVs in it, and half the time I wasn't even sure which character was the POV character.