Tessie is brought in at the right moment to shape the character plot in a certain way, as in any book including a plot relating to humans.<span />
The answer to your question would be the following one:
Cambridge dictionary defines "prevalent" as "existing very common or happening often". As regards "widespread", it states that it means "existing or happening in many places and/or among many people".
With respect to "requisite", Cambridge dictionary states that it is an adjective which means "necessary or needed for a particular purpose". As you can see, "necessary" is part of the definition of "requisite".
Finally, "propagate" is defined as "to spread opinions, lies, or beliefs among a lot of people". As you can see, "spread" is part of the definition of "propagate".
Prevalent: Widespread
Requisite: Necessary
Propagate: Spread
They are speaking of only real events which makes it nonfiction.
