He has grown afraid of Harry's connection to Voldemort. Perhaps Voldemort, knowing Dumbledore's love for Harry, would possess Harry and provoke Dumbledore to kill him. So, Dumbledore attempted to avoid Harry throughout Book 5 for Harry's own good.
And so it is nearly certain that from the night James and Lily were killed, Dumbledore planned for Harry to die ' and not only to die, but ideally to sacrifice his life willingly as Lily had done in order to afford the Light side the greatest chance of destroying the self-proclaimed Dark Lord.
The Hogwarts headmaster kept secrets from Harry that ultimately led him into grave danger. Instead of asking for help from the skilled wizards around him, Dumbledore just did what he wanted.
He had to fight his own morality and ethics knowing it was the only way to beat Voldemort, and he ultimately sacrificed his own life for that cause as well. Which is what makes things a bit better. Means he did not ask things of Harry which he himself was not prepared to give.
Dumbledore now knows what he meant by going further than anyone else in overcoming death. Worse still, he now knows or at least strongly suspects that Harry is also a horcrux, and that he will therefore have to die in order to kill Voldemort for good.
Draco Malfoy's mother Narcissa was cold, cunning and devoted to the Dark Lord. But she was also a mother, which meant she was willing to risk everything to make sure her son was safe. When Harry survived Voldemort's Killing Curse for the second time, Narcissa pretended he was dead so she could get to Draco.
However, Draco was ordered by Voldemort to kill Dumbledore. Lestrange saw this as an opportunity to test Snape's loyalty and while making this vow to always watch over Draco, Lestrange forced Snape to agree to killing Dumbledore himself in case the youngster was unable to do so.
Dumbledore reveals how thoroughly he loves Harry. Harry is brave, and Dumbledore is proud as any father would be. More than that, Dumbledore succumbs to a parent's weakness; he cares more about Harry's happiness and wellbeing than the wizarding world he is trying to protect.
We know now that it was a mistake for Dumbledore to have trusted Snape. We were so sure that there was a good reason for his belief that some of us –– myself included –– were guessing that at some point Snape would not only make his good intentions clear, but drop his bitterness and animosity as well.
Remember, Dumbledore knows about the power of love. The writers merely threw it in as a way of confirming Harry and Hermione are merely friends, a crude way of beginning the courting process between Ron and Hermione, and also Harry and Ginny.
In Harry Potter and the Deathly Hallows, Dumbledore reveals that this had been the Dark Lord's gravest mistake. By using Harry's blood, he took Lily's sacrifice within himself, providing Harry with a tether to life. Harry could not die while Voldemort lived.
Lucius Malfoy had a strong dislike of Albus Dumbledore. This is due to two reasons – Dumbledore believed in Muggle rights which contradicted Malfoy's pure blood beliefs. In addition, Lucius was a Death Eater, so he believed that Lord Voldemort was a much more powerful wizard than Dumbledore.
For all intents and purposes, this act only solidified Harry's suspicions that Snape was working against Dumbledore the entire time. But there were parts of the story Harry didn't know, including that Dumbledore was already dying and had asked Snape to kill him when the time was right.
Despite his attraction to the Dark Arts and Voldemort's ideology of wizard supremacy, Snape's love for Muggle-born Lily Evans, Harry's mother, eventually compelled him to defect from the Death Eaters. He then became a double agent for Albus Dumbledore and the Order of the Phoenix.
He doesn't trust Snape as Dumbledore does, but he believes that he can detect any disloyalty. Moreover, Voldemort regards Snape as highly intelligent and therefore ' as a true Slytherin ' a person whose top priority is to take care of himself. To his twisted mind, selfless equals stupid.
After her death, Dumbledore convinced him that the only way he could remain loyal to her and her memory was to keep her son safe. And D convinced Snape that the only way he could do that was to become part of Dumbledore's plan. So yes, Snape was loyal to D because he had no other way to be true to himself and to Lily.
Some might argue that Snape did it to play the part of a merciless teacher and pretended to hate Harry for having killed Voldemort, so he would not come under suspicion of being allied with Dumbledore. But it's pretty clear that he treated Harry like dirt to get revenge on James.
One of the most famous revelations about Dumbledore after the books were published was that he was actually in love with Gellert Grindelwald.
Why did Dumbledore not tell Harry that he was a Horcrux? It appears that Dumbledore was afraid of Voldemort finding out that he knew about the Horcruxes. At the end of Deathly Hallow Harry realized that Dumbledore also did not want to waste anyone else's life.
The patronus of Snape here signifies his love for Lily and that his only motivation for protecting Harry was because he was Lily's son. In a way, yes. Mostly, especially to start with, he only took care of Harry for his mother, Lily, the love of his life.
He played the part of a loyal servant to Voldemort so well that Voldemort thought of Snape as his most loyal and capable servant. He regretted the (supposed) necessity of losing his (supposed) most valuable servant. He felt nothing for Snape as a person — the only person who mattered to him was himself.
Because Voldemort literally took over the Ministry of Magic. And immediately after Dumbledore's death, Snape disappeared with the rest of the Death Eaters from the Astronomy Tower. The Ministry had a hard time tracking any of the key players in Voldemort's ring.