Peter F. answered 07/30/20
Published Author; Kinder-College English Tutor w/ 18 Years' Experience
Paragraphs in general are very topically oriented. Anytime you move from one topic to another within the context of a piece of writing, a new paragraph must be created.
The same holds true for dialogue in literary works. A new character speaking calls for a new paragraph to be written. Paragraphs like those containing character dialogue are sometimes very short in length. Even introductory and concluding paragraphs in an essay or research paper can be of slimmer lengths if the points they are trying to raise or finish are more succinct in nature, and such paragraphs themselves each merely serve as a means of beginning or ending the piece of writing at hand on a solid, straightforward point.