So, you have this great scene in mind between your two lead characters? Great! I’m a sucker for good conversation. Except that’s only true when the dialogue follows the conventions of English.
Let’s review the guidelines for written dialogue, shall we?
Every time a new person speaks, he/she is indented on a new line (and because WordPress won’t let me indent, I’m using XXXXX to show where you would indent):
XXXXX “What are you doing?” Samantha asked, peering at her husband from her distant perch on the chair across the room.
XXXXX “Rearranging matches,” Sebastian answered in a bored tone, his fingers continuing to move slowly back and forth across the table top.
XXXXX “Why?” Samantha inquired, a small bubble of curiosity balancing atop a storm of frustrated derision.
XXXXX “I have no idea,” Sebastian admitted, pushing the matches into a pile and leaning back into the cushions.
When a character speaks both before and after an interjection, the punctuation should look like this:
XXXXX “You never have any idea,” Samantha sneered, “and that’s why I’m leaving you.”
XXXXX “You can’t leave me,” Sebastian replied, “because if you do, who will organize your things?”
Unless it’s a complete sentence after the break, which would look like this:
XXXXX “You never have any idea,” Samantha sneered. “That’s why I’m leaving you.”
XXXXX “You can’t leave me,” Sebastian replied. “If you do, who will organize your things?”
If you have more to say beyond the spoken words, it can stay in the same paragraph as long as it relates to the same speaker:
XXXXX Samantha glared at him. “I don’t need anyone to organize my things,” she snapped. “I was just fine in my organizational skills before you came along. I don’t need someone to look after me like a child.” She scanned the library, her haughty eyes taking in other annoying details of his obsessive compulsive disorder.
XXXXX “Huh,” Sebastian scoffed. “You couldn’t tell that from where I was standing, dear.” He turned away from his latest project to stare at her. As usual, her clothes were in disarray, her wrinkled pants and untucked shirt almost screaming her need for his guidance. “Come here, Sam. You look a mess.”
XXXXX “You could use a good mess!” Samantha shouted, then she stalked angrily from the room.
Remember that all periods, commas, question marks, and exclamation points go inside the quotation marks in American English (British English follows different conventions. That may be why your Harry Potter or Lord of the Rings looks different).
Note: There is never a reason for “double” “quotation” “marks” next to one another unless you are making a list of quoted items (My favorite poems are “The Raven,” “Love Song of J. Alfred Prufrock,” and “Wedding Ring.”). Everything spoken aloud at one time can go between one set of quotation marks.
I look forward to reading your properly formatted dialogue!