saying he is more “an antique Roman than a Dane” (line 342), Hamlet prevents him, insisting that Horatio must remain to tell his story. Horatio’s words allude to Roman tragedies, including Shakespeare’sJulius Caesar, in which Roman generals would often kill themselves when their cause was lost.

After Hamlet dies, the final two deaths are announced, as an ambassador arrives to tell Hamlet that Rosencrantz and Guildenstern are dead. Young Fortinbras arrives and the plot of the play is finally resolved. Hamlet has a running theme of revenge, specifically that of sons avenging fathers, which is brought to completion by Young Fortinbras arriving to avenge his father, who was killed by Hamlet Senior before the play begins. Laertes has killed Hamlet, who killed Laertes’s father Polonius, and Hamlet has killed his uncle Claudius. Revenge is achieved by all, but Shakespeare suggests at a great cost.

Revenge was considered very sinful by Elizabethan society, who interpreted the Bible verse “To me belongeth vengeance” (King James Bible, Deuteronomy 32:35) as God’s claim on all right to revenge. So naturally, Shakespeare depicts humans taking revenge into their own hands as having epic and tragic consequences, as Hamlet ends with not only the end of one family, but of an entire kingdom, as Fortinbras’s army arrives from Norway. Shakespeare emphasizes this through the aforementioned reference to ancient Roman tragedy, but also through reference to Biblical tragedy. Horatio alone is left to tell Fortinbras what has occurred, a situation that is strongly reminiscent of the Biblical story of Job, where one servant survives to tell Job that all his children have been killed. It’s a connection that will be picked up again in Herman Melville’s novel Moby Dick, as Ishmael alone survives to tell the story of Ahab’s quest for revenge against the whale. 

Hamlet is a tortured soul. His father's ghost keeps visiting him and he learns that his uncle, Claudius, is the one who killed him. Claudius has now become king and married Hamlet's mother. Hamlet is bent of revenge, but it can be said that Hamlet was not crazy. He was a man driven by grief and revenge for the wrongs that were done to him.

When Ophelia commits suicide after her father's death, her brother, Laertes, comes and is angry and the king tells him that it was all Hamlet's fault. Laertes agrees to a sword fight with Hamlet and the king has dipped the tip of the sword with poison. He has also poisoned a goblet of wine in case Hamlet doesn't get cut by the sword. After Hamlet and Laertes are both cut by the sword, Laertes tells Hamlet the truth. He tells him that Claudius is the one behind the death of his mother and is the one who poisoned the sword. Hamlet rams the sword through Claudius and forces him to drink the poisoned wine, eventually killing him. Hamlet succumbs to the poison from the sword, but tells Horatio that he wants it to be known what really happened there. Horatio tells Fortinbras, the Norwegian prince, the whole story of Hamlet. Fortinbras orders that Hamlet be carried away in a manner fitting a fallen solider. 

Hamlet is such a tragic story. Hamlet was a man bent on revenge on the wrongs done to the people he loved. He was not crazy, he was just a man that loved his family and wanted justice for them.

As many of Shakespeare's plays end "Hamlet," is a tragedy with a great deal of death in the conclusion. The queen is dead from poison that was meant for Hamlet.  The king is dead of poison that was forced down his throat by Hamlet in revenge for the death of his father and now his mother.   Laertes tells Hamlet that they both will die because the rapier that each was cut with had been dipped in poison.  Fortinbras finally arrives home and finds out that he will finally be king, but he is really sad about it because he was good friends with Hamlet.   Hamlet tells Horatio to make sure everyone knows what happened to his family and what really went on so there will be no misinformation passed on to future generations.

 ”Fortinbras orders Hamlet’s body carried “like a soldier” to the stage, and says if Hamlet had had the chance, he would “have proved most royal.” He orders appropriate funeral rites for Hamlet, including the firing of ordnance, which ends the play.”

The end of Hamlet is a pretty grim affair, with Hamlet, Laertes, Claudius, and Gertrude all dying. The first to go is Gertrude, who drinks the poisoned cup of wine that the wicked Claudius had prepared for Hamlet. Gertrude was toasting her son during his duel with Laertes, and despite being told by Claudius not to drink the wine, she did so anyway, leading to her death.

The duel goes on, and in the ensuing melee, Hamlet's and Laertes's swords switch so that the poisoned blade that Laertes was going to use to finish off Hamlet ends up in Hamlet's hands. During the fight, Hamlet fatally wounds Laertes with the poisoned tip of the blade. At the same time, Gertrude drops dead, having drunk the poisoned wine.

Now, it's confession time. The dying Laertes tells Hamlet all about Claudius's dastardly murder plot. At long last, after procrastinating for virtually the whole of the play, Hamlet finally gains his revenge on the man who murdered his father. He runs Claudius through with the poisoned blade and forces him to drink the poisoned wine that killed Gertrude.

It's now time for Hamlet to die, wounded as he has been by Laertes's poisoned blade, the very same poisoned blade that has already claimed two lives. With his dying words, Hamlet instructs his good friend Horatio to tell the tale of what happened.

At the end of Hamlet, Laertes challenges Hamlet to a fencing contest, which Laertes and Claudius have already fixed so that Hamlet will die no matter what. Laertes has tipped his fencing foil with poison so that if he but scratches the prince, Hamlet will die of the poison. Claudius adds a poisoned pearl to a cup of wine so that, when Hamlet gets thirsty from the fighting, he will ingest poison in that way too.

During the fighting, Gertrude, Hamlet's mother, raises the poisoned cup to toast to her son, and though Claudius tells her not to drink, she does so anyway. He knows that she will die and that there is nothing to be done now to save her. Laertes and Hamlet resume their contest, and Laertes wounds Hamlet, but they switch weapons during their scuffle, and Hamlet wounds Laertes with the poisoned blade. At the same time, Gertrude falls to the floor, and she cries out, saying that it is the drink that has killed her. After the queen dies, Laertes confesses everything. When Hamlet learns of Claudius's role in this, he wounds the king with the poisoned foil and forces some of the poisoned wine down his throat. The king dies, followed by Laertes.

Hamlet and Horatio speak during Hamlet's final moments, and Horatio would prefer to drink the poison himself so that he could follow Hamlet to death, but Hamlet will not allow him to do so. Hamlet directs Horatio to tell the story of what happened here, and so Hamlet dies. Young Fortinbras and ambassadors from England arrive, and when Fortinbras sees that the entire Danish royal family is dead, he says,

With sorrow I embrace my fortune.
I have some rights of memory in this kingdom,
Which now to claim my vantage doth invite me.
(act 5, scene 2, lines 431–433)

In other words, Fortinbras has some old claim to the Danish throne, and he will rule Denmark now, restoring some order to the kingdom after all of the corruption and death.

Hamlet accepts Laertes' challenge to a duel.   Hamlet is pricked with Laertes sword, which is laced with poison. They take a break and the King urges Hamlet to drink from the poisoned cup.  Instead, Hamlet's mother takes the cup and drinks it.  Quickly thereafter, she dies.  Laertes tips Hamlet off as to why she died; he also lets Hamlet know he's a dead man because of the poisoned sword.  Hamlet forces the King to drink from the poisoned cup so that he dies too.  Then, as Hamlet dies, he forgives Laertes, tells Horatio to tell his tale, and dies.  Hamlet, the King and Queen, and Laertes are all poisoned in the last act.  It is understood that then Fortinbras comes in to pick up the pieces of the shattered kingdom

A lot of things happen, all in quick succession. Osric brings Hamlet an invitation to fence with Laertes, and Hamlet agrees. The duel will happen before the court and, when it does, everything comes apart. To be specific, Claudius poisons a cup of wine hoping to kill Hamlet that way. However, Queen Gertrude drinks it, accidentally killing herself. Laertes is using a poisoned blade. He wounds Hamlet, then they scuffle and end up swapping swords, and Hamlet wounds him. When Laertes asks forgiveness, pointing blame to Claudius, and Hamlet realizes that he's been betrayed again, Hamlet stabs his uncle with the poisoned blade. By the end of Act V, Hamlet, Gertrude, Claudius, and Laertes are all dead; Fortinbras is handed the Crown of Denmark thus according with Hamlet's last request.

I think you are asking for things that have an influence on Hamlet's behavior and attitude in the play.  If so, here are a few things to consider.

One strong influence on Hamlet are his religious beliefs.  He vehemently opposes the marriage of his mother and his uncle because he regards it as incestuous, as would have the Catholic church at the time.  He also considers suicide, but doesn't do it because it is against God's laws.

The ghost influences Hamlet to take vengeance on Claudius for his murder.  He makes sure to tell Hamlet exactly what happened to him and how he feels about the marriage of his wife to his brother so that Hamlet will feel the emotional tie to his father and do what he is told to do.  When the ghost returns in Act 3, Hamlet is influenced to stop being so harsh with his mother and focus his attention on the task of vengeance.

Fortinbras influences Hamlet from afar.  Hamlet sees Fortinbras going off the Poland to fight over a worthless piece of land and Hamlet is then inspired anew to take his vengeance against Claudius -- to fight for something that is very worthwhile and dear to him.

Claudius influences Hamlet to do he needs to do to save himself.  Hamlet reads Claudius's note intended for the English king, and decides re-write the note to condemn Rosencrantz and Guildenstern.  This isn't something he would have done in other circumstances, but Claudius kind of forces his hand.