Title: Just A Good 'Ole Boy
As a late comer to the world of Smallville, I was introduced to Season Three Jonathan Kent long before I got to know the man as he was in the first two seasons. By the time I arrived to the party, Mr. Kent had already suffered a heart attack, and had lived through the myriad of changes in Clark's powers and behaviors. The Jonathan Kent I got to know first had greatly mellowed by this time.
My first impression was that the man, while almost desperate to hold onto his very small town values and Amish like existence, was also beginning to evolve into a more well rounded man, capable of seeing past a person's faults to who they really were inside. This was clear when Pete Ross, while under the influence of the alien insect, shouted out to the entire town that Clark is an alien, yet at the end of the episode Jonathan forgives him. "Besides, everyone stumbles. The important thing is that you’re safe, you’re alive, and you’re still a member of this family."
The man struck me as strong of mind, will and body. His values are deeply ingrained and his most torturous conflicts arise when those values are put to the test, or he has to put them aside to deal with a situation. His love of family is extremely strong, making him the perfect contrast to Lionel's love of self, and Jor-El's quest for dominion. To me, this was most clear when he went to Jor-El, his only real competitor for the paternal love from his son, to obtain help in getting Clark back in the episode 'Red'. Then it shines clearly again when he attempts to intervene between Jor-El and Clark in Covenant.
This is not to say that Jonathan hasn't made bad decisions, or even knowingly gone against his own beliefs and ethics. The most perfect example of this comes when we learn of his coercion of the Rosses into selling out to Lionel Luthor in exchange for his help in 'legalizing' Clark's adoption. This is where we first see that his greatest weakness is his love of his family. He would do almost anything to attain Martha's greatest desire, and sacrifices his ideals and morals to do so. His hatred of Lionel Luthor is born here, and, as he is unable to separate the man from his son, his distrust spills over onto Lex. Another great weakness Jonathan presents is his pride. The man is overflowing with it; to the extent he'd rather take chances with his own health than accept help from Lex. This is not the first instance, however. We learn in later episodes that he was just as adamant about refusing assistance from Martha's father.
"Your destiny may be to protect people, but ours is to protect you, and that's gotta come first." From the beginning we see that Jonathan is supremely protective of Clark and his secret, to the point of keeping that life altering information secret from even his son until the incident on the bridge. He works as hard at keeping Clark safe, and making certain his son knows the consequences of being 'outed' as an alien as he does at keeping the farm solvent. Though he may seem harsh at times, it is his very unwillingness to bend on certain matters that help to shape Clark into the man with the sense of moral rightness that he will need to become Superman. Having to be so very careful of every word spoken in public, and having to be constantly hyper-vigilant that a powerful child didn't leave evidence of his 'gifts' everywhere; "The first time Clark used his abilities, he'd crawled under a big oak bed that my grandfather had made and I crawled underneath it to try to get him out and all of a sudden the frame just came up in the air...and he was a toddler lifting - I don't know - five hundred pounds over his head.", they went does seem to have made Jonathan overprotective. He doesn't allow Clark to participate in sports for fear of someone finding out Clark's secret, and though many have expressed their view of this as him being unfair to Clark, it is only done with Clark's best interest in mind. He would have loved to have had children of his own. He would love for Clark to have a 'normal' life. Neither of these things is possible, though, and he rises to the challenges of being an adoptive parent of a very special little boy with grace and strength of character.
Keeping in mind that is written from my point of view, and that my views are shaped by growing up and raising my own children in an environment very similar to Smallville (save the mutants, unless you count idiot ex-husbands in that group), I can easily see how and why Jonathan makes many of the choices he makes. The general consensus, from what I have gleaned from friends lists, and talking with other Smallville viewers, is that the man simply can't die fast enough to suit them. I disagree, in that I don't think Clark is ready to face the world without the steadying influence of his earthly father. Yes, the pious attitude and platitudes; "The road to Hell is paved with good intentions!", have worn very thin, yet it is these very platitudes that Clark remembers and uses as a moral rudder when he's facing situations alone.
It is also my opinion that John Schneider is a perfect Jonathan Kent. I can't think of another actor better suited to this role. While I grew up with him as Bo Duke, another character based on a small town upbringing, I see the maturity and confidence he brings to his Smallville role as more of who he really is as a person. He is a father and a husband in real life, and he grew up in the same small town atmosphere and he uses these experiences to give us a very real sense of who Jonathan Kent is.