How is Hamlet selfish and manipulative?i.e. ways in which he does not care about the effects of his actions
In Shakepeare's magnificent play, it becomes apparent that Hamlet's noble nature waivers at times because of the grave injury it suffers. Having learned of his father's assassination, he is repulsed by the weakness and sinfulness of his mother in marrying her brother-in-law, the treachery of his friends and love, Ophelia, and the corruption of the Danish court as exemplfied by Polonius, Laertes, and others. Feeling himself under attack from his world, Hamlet reacts with a certain narrowed self-protectiveness and a cruelty born of his injury. This cruelty focuses itself mainly upon Gertrude, Ophelia, Polonius, and Rosencrantz and Guildenstern.
In his private invective against his mother, Hamlet fears that Gertrude may have been involved in the murder of his father:
O most pernicious woman!
O villain, villain, smiling, damnèd villain!
My tables—meet it is I set it down
That one may smile, and smile, and be a villain—
At least I am sure it may be so in Denmark. (1.5.105-109)
And, so, feeling threatened by his mother, Hamlet vows that he wil "wipe away all trivial fond records" (1.5.102) of his youth and act defensively toward Gertrude. Thus, in subsequent scenes, such as Scene 4 of Act III, he berates his mother for marrying Claudius:
What devil was't
That thus hath cozen'd you at hoodman-blind?
Eyes without feeling, feeling without sight, (3.4.83-85)
Because Ophelia loves Hamlet, but becomes a pawn to her father's machinations, Hamlet's cruelty towards her seems the most acrimonious. Offensive and even indecent in his words to her in return for the hurt she causes him when she returns "remembrances" to Hamlet, Hamlet denies having loved her and, in his misogyny orders her to go to a convent and live out her life:
If thou dost marry, I'll give thee this plague for thy
dowry: be thou as chaste as ice, as pure as snow, thou shalt
not escape calumny. Get thee to a nunnery. Go, farewell. Or
if thou wilt needs marry, marry a fool; for wise men know
well enough what monsters you make of them. To a nunnery,
go; and quickly too. Farewell. (3.1.145-149)
Yet, in this scene there is a certain protectiveness that underlies this cruelty. But, Hamlet's virulence is pronounced in Scene 2 as he asks lewd questions of her and makes bawdy innuendos in order to embarrass her and reject her.
In Act III, Scene 4, when Hamlet accuses his mother of unfaithfulness to his father and Polonius moves from behind the arras, Hamlet impetuously draws his sword crying, "How, now, a rat?" (3.4.22) and slays the spy. Without remorse for his act, Hamlet tells his mother, "I'll lug the guts into the neighbour room (3.4.216).
Rosencrantz and Guildenstern
Former boyhood friends of Hamlet, Rosencrantz and Guildenstern are opportunists who are easily persuaded to betray Hamlet. However, Hamlet suspects them of their subterfuge and quickly constructs a counterplot, having them go to their deaths instead. This act against Rosencrantz and Guildenstern is more self-preservative than cruel, but Hamlet certainly manipulates them well. Added to this is the fact that the two men could have destroyed the letter that condemns Hamlet, but not understanding the world that they are in, they do not. Thus, they become pawns in the corruption of the Danish court, and, as such, suffer the consequences of Hamlet's determined plans to rid Denmark of its rottenness.