Explain the characteristics of fires with different origins, i.e.?

Question

slow fires
rapidly developing fires
accidental fires from different causes

Answer 1

to broad a question for specific answer. fire requires three things, heat fuel and oxygen. insufficient amount of any of these can cause a fire to smolder.using a wildland fire as a basis you can develop further scenarios.
lightening hits tree (heat) and ground is slightly damp (retarding fuel) small wind comes up and dries out fuel on ground, this has added both dryer fuel by removing the moisture, and adding larger quantities of oxygen. Now your smoldering fire has become rapidly developing fire.

The things that are most static in the fire triangle of heat fuel and oxygen are fuel and oxygen. Look in your trash basket, it is a possible fire source, just add heat sufficient for some item to burn.

look at a cooking or heating stove, drop a paper plate on a stove top burner which is on, smolders until fire breaks out.

with these examples you should be able to developer any number of examples to fit your needs.

Note, any good fire investigator knows how to spot these and determine source for arson purposes