The Volturi arrive in rigid, perfectly synchronous formation, "a dark, unbroken shape that seemed to hover a few inches above the white snow, so smooth was the advance" (36.2). They show no surprise at the collection of vampires and werewolves before them.
Bella counts thirty-two Volturi against nineteen fighters on the Cullen side. Behind the Volturi, more vampires appear. It turns out, the Volturi brought their own witnesses. Bella now believes that all is lost:
Even if we could somehow neutralize the Volturi's advantages, they could still bury us in bodies. (36.15)
On the other side, Irina is horrified to face her sisters. Edward's now convinced that the Volturi have come to destroy and acquire:
They have many layers of strategy already in place. If Irina's accusation had somehow proven to be false, they were committed to find another reason to take offense. (36.21)
When the werewolves appear (sixteen total), the Volturi come to a stop. Bella realizes that Sam brought his entire pack, because he knows that the Volturi would hunt down the rest. It pains her to image that the young werewolves will die in a fight they're surely going to lose. The injustice of it all suddenly makes her murderously enraged:
All I wanted in that moment was the chance to sink my teeth into them, to rip their limbs from their bodies and pile them for burning. (36.29)
She's now ready to fight, focusing on Alec and Jane.
Carlisle meets Aro, the Volturi leader, halfway. His bodyguard, Renata, accompanies Aro. Carlisle explains to him that no law has been broken. "[Renesmee] is not an immortal. She is not a vampire" (36.62). He explains that their friends are just witnesses to the truth of Renesmee's nature, and are not here to fight.
Aro calls Irina to the front. Seeing Renesmee, she admits that the child she remembers was smaller. Aro asks for Edward to step forward, so he can read his thoughts. Catching Jane's smug smile as Edward nears the Volturi, Bella's fury peaks and she throws out her shield:
…my shield exploded a good fifty yards out from me effortlessly, taking only a fraction of my concentration. I could feel it flex like just another muscle, obedient to my will. (36.96)
After reading Edward's thoughts, Aro realizes that Carlisle has spoken the truth. He asks to meet Renesmee. They bring her forward, guarded on both sides. Aro compliments Bella on her new looks. "Immortality suits you" (36.149). He praises Renesmee's beauty and explains to his brother Caius that Renesmee is Bella and Edward's biological child. But Caius believes they've been tricked. Aro communicates with Renesmee.
His eyes suddenly move to Jacob, and the werewolves. Edward gathers that Aro thinks that the werewolves would make great guard dogs for the Volturi. Edward tells him that they don't follow vampire commands and are committed to protecting human life.
Aro informs Edward that he'll have to confer with his brothers on this change of events.