The first paragraph of OMW is excellent: "I did two things on my seventy-fifth birthday. I visited my wife's grave. Then I joined the army." (OMW p7) Immediately the reader learns the protagonist's age, the fact that he's a widower, and the fact that he's willing to fight for his country--or planet, as we find out later. Both the facts that he's a widower and he's willing to fight to protect others makes him sympathetic right off the bat, moreover, the reader identifies with, i.e. empathizes with, him because he's sympathetic. The author also piques the reader's interest with a seeming inconsistency: how can a seventy-five year old join the army?
In chapter two, Scalzi uses a device to make characters more sympathetic, namely, they thwart a very unsympathetic character: Leon says, "There's nothing in the Bible that says we should be stuck on Earth while a bunch of brownies, which don't even believe in Jesus, thank you very much, fill up the galaxy. And it certainly doesn't say anything about us protecting the little bastards while they do it." (OMW p26)
John says, "But I say unto you, Love your enemies.... Bless them that curse you, do good to them that hate you, and pray for them which despitefully use you, and persecute you; That ye may be the children of your Father who is in Heaven: for he maketh his sun to rise on the evil and on the good, and sendeth rain on the just and on the unjust..." (OMW p26)
And in response, "Leon turned lobster red. 'You're both out of your fucking gourds,' he said, and stomped off as fast as his fat would carry him." (OMW p26) This scene works very well to endear the reader to John because Leon is so unpleasant and 'the enemy of my enemy is my friend'.
When other people like the protagonist, the reader likes the protagonist. Thus John collects friends such as Jesse, Harry, Thomas, Susan, Maggie, and Alan, and they all have an easy camaraderie. For example,
"This is my roommate, Alan Rosenthal," he [Harry] said, by way of introduction.
"Formerly known as Sleeping Beauty," I said.
"About half of that description is right," Alan said. "I am in fact devastatingly beautiful." I introduced Harry and Alan to Susan and Thomas.
...Harry said to me ...."...Alan here is a theoretical physicist. Smart as a whip."
"And devastatingly beautiful," Susan piped in. (OMW pp48-9)
A significant way to make characters appealing is to show them caring about others. Scalzi does this extremely effectively:
...we became friends, and close friends at that, in the short period of time we had together. It's no exaggeration to say that I became as close to Thomas, Susan, Alan, Harry, Jesse and Maggie as I had to anyone in the last half of my 'normal' life. We became a band, and a family... We gave one another someone to care about, which was something we needed in a universe that didn't know or cared that we existed. We bonded. ...And as the Henry Hudson drew closer to our final destination, I knew I was going to miss them. (OMW p105)
When John's band of friends, the Old Farts, get assignments in other parts of the galaxy, they resolve,
"Let's do it," Harry said. "Let's be our own little family. Let's look out for each other, no matter where we are."
"Now you're getting misty, too," Susan said.
..."A pact, then," I said. "To stay the Old Farts, through thick and thin. Look out, universe." I held out my hand. One by one, each of the Old Farts put their hand on mine.
"Christ," Susan said, as she put her hand on the pile. "Now I'm misty."
"It'll pass," Alan said. Susan hit him lightly with her other hand.
We stayed that way as long as we could. (OMW p109)
Thanks to Scalzi, the reader also feels like part of the family and gets 'misty' as well.
These personal relationships are utilized effectively throughout the remainder of the book. The reader feels sorry for and sympathizes with John when his new family meets with disaster, for example, "Maggie was the first of the Old Farts to die." (OMW p162) John describes Maggie's death:
She was my friend. Briefly, she was my lover. She was braver than I ever would have been in the moment of death. And I bet she was a hell of a shooting star. (OMW pp163-164)
In Part II of OMW, Scalzi changes gears a bit and shows his characters at war. A reader instinctively admires a character that protects others. These characters are, moreover, sympathetic because they are realistically afraid but continue to fight to defend humanity anyway. Isn't that the epitome of courage? John has a very difficult time in his first battle when his fellow soldier Watson is killed, which the reader can empathize with.The reader furthermore wants to identify with John because he turns out to be a very good soldier. For example, in the first battle, he discovers a way to kill the enemy by using two shots. "I forwarded the firing specification to Watson and Viveros; Viveros forwarded it up the chain of command." (OMW p155) "We won. The double-bullet rifle technique thinned out the Consu herd by a substantial amount..." (OMW p157) John continues to be an admirable soldier with good ideas for the rest of the novel.
In part III, Scalzi creates a final, very effective, aspect to John's characterization which is introduced when John is near death:
A warm hand on the side of what's left of my face. "Hey," the familiar voice says. "Hey. You're all right now. It's okay. ..."
Her face comes into view. I know the face. I was married to it.
Kathy has come for me.
I weep. I know I'm dead. I don't mind. (OMW p211)
John suffers and the reader suffers through him and for him.
When John approaches the mysterious woman for the first time the reader is right there with him:
I stopped as I got a look at her face...
"It's not nice to stare," the woman said, using Kathy's voice. ...
"I'm sorry, I don't really mean to intrude,” I said. "I was just wondering if you might recognize me."
She flickered her eyes up and down on me. "I really don't," she said. (OMW 234)
Again, the reader feels for John.
Since Scalzi knows what he's doing, this Kathy/not-Kathy issue is resolved by the time OMW concludes.
Therefore, in OMW, Scalzi uses every trick in the book (except maybe saving babies and/or puppies) and successfully shows us John's actions, speech and thoughts to make the reader care about him. Kudos, Mr. Scalzi.