Rowling stated in an interview that Lupin and Tonks died to compensate for the last-minute reprieve she gave to Arthur Weasley when he survived a would-have-been fatal attack in Harry Potter and the Order of the Phoenix. Rowling also stated that it was Antonin Dolohov who killed him.
While it is unknown exactly which curse Dolohov used, he fired the spell that murdered Remus Lupin. There has been debate over the years on whether Dolohov used the Killing Curse or some equally horrifying curse of his own design. Either way, he caught Lupin off guard, and his life was forfeit.
Remus fought at the Battle of Hogwarts on 2 May 1998, during which his wife was murdered by Bellatrix Lestrange. Remus was also murdered by Death Eater Antonin Dolohov, during the first half of the same battle. His death was possibly avenged by Filius Flitwick.
In 1998, Dolohov fought in the Battle of Hogwarts, during which he murdered Remus Lupin. At the climax of the battle, he engaged Filius Flitwick in a duel and was defeated.
Why wasn't Tonks and Lupin's death scene shown in "Harry Potter and the Deathly Hallows – Part 2"? Because it wasn't in the books either. Very few actual death scenes are shown in the books and specifically during the Battle of Hogwarts there were 50 deaths, of which we witness Voldy's and Bella's.
How Did These Harry Potter Characters Die ? (Remus Lupin, Peter Pettigrew, Gellert Grindelwald ... )
Who kills Bellatrix?
During the final battle, Bellatrix was the last Death Eater standing. She was eventually killed in a duel by Molly Weasley after her attempted murder of Ginny Weasley. Before her death, Bellatrix secretly gave birth to an illegitimate daughter named Delphini, whom she conceived with her beloved master, Lord Voldemort.
Nymphadora Tonks married Remus Lupin in 1997 and they had a son. He was named Teddy, after Tonks's father. It was obvious that Tonks loved her son very much. Teddy was a Metamorphmagus, like his mother.
Sirius was only 36 years old when he tragically died at the hands of Bellatrix Lestrange. Since most of the adult Harry Potter actors were older than their characters, the age changes in the films helped hide just how young Sirius actually was.
Fred was killed in an explosion possibly caused by Augustus Rookwood. One of the last things Fred heard before dying was Percy joking about resigning from the Ministry. Percy wouldn't leave Fred's side until Harry and Ron helped him move the body to somewhere safer, coincidentally behind a suit of armor.
In the film, Bellatrix hit Sirius with the Killing Curse, Avada Kedavra, killing him before he passes through the Veil. In the book, the curse that hits Sirius is not identified (although it is rumoured to be Stupefy because of the red light), and him being knocked through the Veil is what causes his death.
In the EXCELLENT James Potter book series, by G. Norman Lippert, Tonks had already given birth to a boy before being killed in the Battle of Hogwarts. (The James Potter in the Lippert series is Harry Potter's son).
For the second time in Voldemort's life, the unforgivable curse rebounded on him, as the Elder Wand wouldn't kill its master. Since Harry and his friends had already destroyed all of Voldemort's Horcruxes, this finally ended Lord Voldemort's life, with Harry finally defeating the Dark Lord.
During a frenzied duel with Bellatrix, Sirius taunts her for failing to harm him. Bellatrix strikes Sirius with a curse, sending him backwards into the veil and to his death. Overcome with grief and rage, Harry tries – and fails – to get revenge on Bellatrix, only to be interrupted by Voldemort's arrival.
As Remus grew, however, so too did his werewolf form. It became increasingly harder and harder to keep him subdued with spells. In the end, Remus's wolf form overcame Lyall's ability entirely. This is why it's useless to use such kinds of spell on an older werewolf.
In the Harry Potter series, Remus Lupin loved his three friends wholeheartedly and felt similarly for James' son Harry. However, that doesn't mean he was the best of mentors to him, either. He felt that because of his condition, he was blessed to have any sort of friends at all, and did nothing against them.
Most of the interactions we see between Snape and Lupin occur during Harry's third year when Snape believes that Lupin is helping Sirius Black into the castle. Snape also thinks that Lupin collaborated with Sirius to try to kill him while they were at school.
His help at the Ministry of Magic might result in a smoother mission. Thanks for A2A. No. Sirius had no idea that Harry was a Horcrux, and I think that is one of the kindest things that was done.
Dumbledore's lack of belief that Sirius is innocent is also suspect. Sirius was a member of the Order of the Phoenix which fought against Death Eaters, but Sirius also was as close to James as a brother, the Potters even took him in when he ran away from home.
As a result, Teddy was raised by his maternal grandmother Andromeda, with help from his godfather. He began attending Hogwarts School of Witchcraft and Wizardry in 2009. During his time at Hogwarts, Teddy was Sorted into Hufflepuff House and in his seventh year was appointed Head Boy.
This was a relief for Lupin. After the war, Teddy was raised by Tonks' mother, Andromeda, but had a close relationship with his godfather, Harry. He was sorted into Hufflepuff and became Head Boy at Hogwarts.
Unlike their book counterparts, the Remus Lupin and Nymphadora Tonks of the films seem to already be a couple during Harry's sixth year as in Half-Blood Prince film the pair travel together and Tonks calls Remus 'sweetheart'.
