Bellatrix Lestrange Killed her own cousin, Sirius Black: She killed Sirius (who was her cousin) during the battle at the Department of Mysteries. She was remorseless and was cackling in glee after she had murdered Sirius.
Bellatrix hates Sirius because he ran away from home and is a "blood traitor", since he doesn't hate non-pure-bloods. Both Andromeda and Sirius were burned off the Black family tree tapestry at their ancestral home at 12 Grimmauld Place. Bellatrix ends up killing her niece Nymphadora Tonks and cousin Sirius Black.
Sirius takes on his cousin Bellatrix, taunting her that she can fight better. Albus Dumbledore arrives and stops most of the fighting, but Bellatrix and Sirius continue. She casts a powerful curse, blasting him in the chest and sending him through the veiled arch.
Okey, we all agree that Bellatrix did not use tha avada kedavra when killing Sirius and that she used stupefy.
Sirius Black couldn't have countered Bellatrix's killing curse becaue the killing curse isn't something that can traditionally be countered with the disarming charm.
When the Dark Lord used Avada Kedavra for the final time in the Harry Potter series, the spell deflected due to Harry's ownership of the Elder wand, killing Voldemort with his own signature spell. Following Voldemort's demise, the Unforgivable Curses were strictly deemed illegal by the Ministry of Magic.
5 Bellatrix Lestrange: The Cruciatus Curse.
Cruciatus Curse ('Crucio')
Harry tried to use this spell himself. The first time was against Bellatrix after she had killed Sirius. His attempt was unsuccessful because, as Bellatrix mockingly explained: 'You need to really want to cause pain – to enjoy it – righteous anger won't hurt me for long…'
His reaction to Bella's death was akin to his reaction at the loss of the Cup, which was when he realised that his own immortality was jeopardised amidst war and his own death could have been near.
Bellatrix's evil nature arises from her blind devotion to Tom Riddle and she is cruel. She enjoys torturing people and is quite frankly, insane. However, she is not as evil as Voldemort as he has transcended beyond limits of evil and dark magic by making not one but 7 Horcruxes.
Voldemort's attempts to trick Harry into killing Bellatrix would have done far more harm than good to his sinister cause, as Harry killing Bellatrix might have resulted in dire consequences for him, but he'd remain one of Voldemort's greatest threats and the Dark Wizard would be missing his most trusted lieutenant.
According to Sirius Black, the people in Azkaban goes crazy there because dementors guard Azkaban. They suck all the happiness out, so they go crazy. Bellatrix ended up in Azkaban because she took part of the torturing of Frank and Alice Longbottom, so she became crazy in there.
Unlike many Death Eaters, when Bellatrix was imprisoned in Azkaban, she did not lie about her loyalty, instead proudly declaring herself to be a follower of Voldemort. Even Voldemort himself had a considerable amount of respect for Bellatrix.
Draco had several reasons for lying to Bellatrix, including the fact that he was never a bad person. Moreover, he no longer found working for the Dark Lord appealing and hated how Voldemort treated his family. He did not intend to harm anyone and believed Harry was the only person capable of defeating Voldemort.
DESTROY: SIRIUS BLACK
In the book, she hits him with a curse, causing him to stumble into the Veil, which proves that she bested him in combat. Sirius was no slouch in the wizarding department, but ultimately, he would have always failed to defeat her. He lacked the ruthless cunning needed to take on Bellatrix.
Avada Kedavra, also known as the Killing Curse, kills a person instantaneously and without injury. There is few counter for it, and only one person, Harry Potter, has ever survived it with Sacrificial Protection that has been endowed upon Harry Potter by His Mother Love for Him.
Why doesn t Harry use Avada Kedavra on Bellatrix? Harry didn't use that spell because he cannot bring himself to kill anyone. He is not a killer.
The author explicitly states that both women were fighting to kill, despite Molly refraining from casting the Unforgivable curse Avada Kedavra. The result of the duel actually comes about as a result of nothing more than spectacular accuracy on Weasley's part.
Bellatrix had a fear of rejection as well where Voldemort was concerned, wanting nothing more than to please him but was always frightened that she would lose his favor.
As the youngest Weasley, we're sure Ginny observed more than her fair share of unpleasant spells over the years but it was the Bat Bogey Hex she was famous for – and with good reason.
If Bellatrix managed to muster affection for anyone other than Voldemort, it was her younger sister (even at the height of the Second Wizarding War, Bellatrix and Narcissa called each other Cissy and Bella, no doubt childhood nicknames they'd given each other).
Draco Malfoy (Cruciatus and Imperius Curses)
Although the use of these curses is rightly unforgivable, it's important to note that Draco never used them for his own benefit. It was always the pressure from Lord Voldemort that forced Draco into his crimes.
Speak to Sebastian in the Undercroft after this and he'll teach you any Unforgivable Curses you have missed up to that point, including Avada Kedavra. It's worth learning the curse as doing so should have no negative outcome on the game's story.