When I was in college I took a class called "Introduction to Creative Writing" and one of the lectures was called "characters". The short of it is: A plot is nothing more than a character in trouble." This resonated with me and I've kept it in mind ever since.
I let the characters drive the story. Their actions, their choices, their desires; I follow them to their logical (or illogical) conclusion. Sometimes I have to rewrite events and even the plot itself to accommodate the characters and their trouble. The story flows better this way.
Furthermore, I personally hate it when an episode of a show or some story arc in a book derails characters to make itself work. It feels forced and unnatural reminds that these people are not real people but actors with a script. It's hard to care about actors with a script and if I don't care about them (and the characters they represent) then why do I care about what happens to them? If I don't care about what happens to them then why am I reading/watching/playing the story?