What really impressed me as I re-read Hamlet was what a devlish schemer King Claudius is! Quite early in the play, we realize -- through Hamlet's eyes and the ghost's witness -- how effectively he has turned Queen Gertrude to his will. It also becomes clear that he sees Hamlet as an enemy, and is willing to turn others against Hamlet. Polonius too does his bidding, though it's not clear if Polonius ever had any backbone. Still, he inspires Polonius to betray Ophelia, his own daughter, in order to manipulate Hamlet and either make him go mad or look mad.
The players' performance is obviously a turning point, where Hamlet tries to warn everyone of the true Claudius. But Claudius seems determined to hold onto his position. In his prayer Claudius says,"O, my offense is rank, it smells to heaven; it hath the primal eldest curse upon't, A brother's murder." So he recognizes his evil. However -- "May one be pardoned and retain th'offense?" he asks, because he won't give up his viciously obtained spoils: "My crown, mine own ambition, and my queen." (III, iii)
But then he continues and compounds his evil. He tries to send Hamlet to England to be killed, but Hamlet returns. His victims are silly Rosenkrantz and Guildenstern -- also inspired by his scheming to betray their friend, before the tables turned.
As the play concludes, Claudius continues to defend his evil spoils. He prods Laertes to seek revenge with a poisoned duelling weapon, and at the same time prepares a poisoned drink, determined to be rid of Hamlet. As everyone knows, all Claudius's plans fail, bringing all but Horatio to their deaths, and returning the kingdom to those whom his nobler brother had once conquered.
We don't have a clue what made Claudius so evil. There's nothing about jealousy of his brother, dislike of his nephew, love of his sister-in-law, or any hint about what he was doing throughout the many years of his brother's long and successful reign. I don't think we are meant to ask these questions. Claudius is a given of Hamlet's environment from the first moment of the play. Maybe that's why I never focused on him before.
I find Prince Hamlet's complex character as fascinating as ever. I find doubly betrayed Ophelia as tragic and romatic or pathetic as ever. But I hadn't thought so much about Claudius before.