I have just re-read the terrific introduction by Norman N. Holland to my dog-eared Signet edition of 2 Henry IV. It is worth reading, but I do not want to lay too much of it on you because going at this play fresh and without undue critical influence is probably a good thing. I would, however, like to mention some of Holland's thematic concerns and other potentially helpful insights.
Holland lays great stress on how radically different 2 Henry IV is from Part 1―especially in tone and in how the characters are used and relate themselves to a larger vision of "how the world goes." Those who do this right end up the winners; those who do not have little more to look forward to than a gaping grave.
Holland also sets forth "betrayal," or, more correctly, "expectation mocked" as a central theme, introduced by Rumor's words and repeated again and again throughout the play. Even Falstaff's cannon-fodder recruits show this in that their satiric names are often the opposite of their natures. (It is, he notes, one of the few plays in which Shakespeare uses a whole bunch of names that are related to people's occupations or social positions.) It can also be seen in the double-sided nature of the Page's answer to Falstaff's "Sirrah … what says the doctor to my water": "He said, sir, the water itself was a good healthy water; but, for the party that [owned] it, he might have [more] diseases than he knew…."
He also raises the question of how, indeed, does one grasp fortune by the forelock and shape it to one's will, suggesting that both Francis Feeble (and a number of the more successful characters) are actually quite stoical in their responses to Fate:
"A man can die but once. We owe God a death. I'll ne'er bare a base mind. And't be my destiny, so. And't be not, so. No man's too good to serve's Prince. And let it go which way it will, he that dies this year is quit for the next." (See this quote used in Howard Hawks' Only Angels Have Wings.)
It is a dark play, says Holland, foreshadowing the tragedies and the sometimes curative suffering so many of Shakespeare's tragic heroes have to endure. There is a keen awareness of humans' relationship to the "gods" or fates King Lear's characters mention again and again, I think. In Holland's view, the play may be a bit more optimistic/presciptive than King Lear, but not terribly. To quote Holland: To raise oneself to the superior perspective, one must gain "… the ability to give up one's own desires, to trust, even to merge and identify with the 'necessity' represented by others, even, in a sense, to tolerate being engulfed by or devoured by it (as King Henry's crown, emblem of the larger order, has eaten its bearer up), than enables us to reemerge, as we did in earliest infancy, into a new sense of identity, a new role. In a paradox almost biblical, we must lose ourselves to find ourselves."
"Enough, or too much."
--William Blake, "The Marriage of Heaven and Hell"