Death Eater Strife
Harry Potter and the Half-Blood PrinceBellatrix distrusts Snape and challenges his loyalty, but Voldemort's trust in Snape keeps the peace.
increasing
Bearing strength in each event
decreasing
The Accusation

The Challenge
The Wrath
Bellatrix Lestrange openly accuses Severus Snape of being a traitor. She lists his past failures: not finding Voldemort after his fall, preventing the Sorcerer's Stone's theft, and not killing Harry Potter.
The Defense
Snape calmly refutes each accusation, explaining his actions were on Dumbledore's orders to maintain his cover. He claims to have passed valuable information to Voldemort.
The Outcome
Bellatrix is not fully convinced, but she cannot prove her suspicions. The tension between them remains. She is a constant threat to Snape's position.
The Thwarted Plan

The Cooperation
The Joint Effort
Despite her distrust, Bellatrix fights alongside Snape during the invasion of Hogwarts. They work together to achieve their goal: killing Dumbledore.
The Escape
After Dumbledore's death, Bellatrix, Snape, and the other Death Eaters flee together. Snape's role is crucial; he is the one who actually killed Dumbledore.
The Aftermath
Bellatrix's suspicion of Snape is temporarily set aside. She reports to Voldemort that Snape fulfilled his mission. The internal strife is suppressed by their shared success.
early July, at Spinner's End
late June, during the Astronomy Tower battle