Fairy tales are chock full of what folklore scholar Donald Haase calls "helper kings." You know the kind. They're powerful and generous and they move the story's plot forward by giving a hero props for some kind of valiant deed. In a lot of these stories, heroes are rewarded for curing the king's illness when no one else can do it. (Ever read "The Water of Life" in Grimms' Fairy Tales?)
In many ways, Shakespeare's king of France is a "helper king." When the play opens, he's dying of an illness that no doctor has been able to cure. When Helen comes along and offers her services, he gives her a shot and then rewards her actions by letting her choose any husband she wants (2.3). The king and his freaky disease are very much at the center of the action in All's Well That Ends Well because Helen's quest to cure him sets the entire plot in motion.
Shakespeare takes a familiar plot device and adds a major gross-out factor and some raunchy humor for good measure. We're just going to come right out and say it: the king's disease is really disgusting. It turns out that he's got what's called a fistula, which is basically a very painful, pus-filled boil. Also, it's probably on his butt, which sort of explains Lavatch's weird "buttocks" joke in Act 2, Scene 2. At least that's what some scholars (like F. David Hoeniger) think. Did we mention that the fistula is so painful that the king can't even walk and has to be carried around on a padded chair? No wonder the 2004 Cambridge production of the play had the King crawling around on his hands and knees yelping in pain and gesturing toward his rear end. ("'Twas mine, 'twas Helen's': Rings of Desire in All's Well That Ends Well," source.)
There's also some evidence that the disease seems to have made the king impotent. This becomes clear in Act 2, Scene 1 when Lafeu kneels before the king and says he wishes the king were healthy enough to "stand up" (get up on his feet/get an erection). Lafeu then tells the king that he knows a doctor who is so skillful that she could "araise King Pepin" (bring king Pepin back from the dead/give him an erection). So, why are we making a big deal out of this? Well, because Shakespeare does. All's Well That Ends Well reminds us over and over again that health and vitality go hand in hand with sexual potency, which is why the king gets all frisky and starts dirty dancing with Helen after she cures him (2.3). What can we say? Shakespeare likes to tell dirty jokes. In doing so, he reminds us that we're not reading any ordinary fairy tale.
Shakespeare doesn't use the sickly monarch just as an excuse to crack a bunch of raunchy jokes. He also uses the king of France as a vehicle to explore some major themes in the play – namely, mortality and old age. When the play opens, the king is not only sick, he's dying. He has also begun to look back on his life and his youth with a sense of nostalgia. At one point, he remembers a dear friend from his youth who has recently died:
Would I were with him! He would always say—
Methinks I hear him now;
"Let me not live," quoth he,
"After my flame lacks oil, to be the snuff
Of younger spirits, whose apprehensive senses
All but new things disdain, whose judgments are
Mere fathers of their garments; whose constancies
Expire before their fashions." This he wished.
I, after him, do after him wish too. (1.2.59-60; 65-71)
Here, the King of France seems both wistful and hopeless (kind of like Shakespeare's aging King Lear or King Henry IV, who, even on his deathbed, is stressed about his son taking over the throne.) He not only longs for his youth, but he also worries about the future because he doesn't think the younger generation is fit to take over. He points out that France's youth are shallow and trendy and don't care about anything of real importance.
At the same time, the king feels helpless because his illness has made him weak and feeble. When the Florentines ask for his help, he doesn't even have the energy to fight in the Italian war (1.2). In the passage below, he says he wishes he were dead so that the new generation could take over and get to work:
Since I nor wax nor honey can bring home,
I quickly were dissolvèd from my hive
To give some laborers room. (1.2.72-74)
Here, the dying ruler compares his kingdom to a hive and describes what will inevitably happen when he's dead: a new group of "laborers" (a.k.a. worker bees) will take over the business of running the kingdom. In other words, he knows that life won't stop when he's gone. It will keep humming along without him, for better or for worse.
Yep. It doesn't get more depressing than that. Even though the king is eventually cured and experiences a miraculous recovery, Shakespeare gives us a brief glimpse of what the future holds for all of us.