Viper

You play as Sage.
Binj's ashes settled on the gas mask lenses, mixing with the acrid sweat. Viper stood over the body, which had already begun to turn to shining dust. Her fingers trembled as she gripped the trigger, but there was no one to shoot.
Chamber is dead.
Not from an enemy bullet. Not from radianite. From Sage's green, healing spark, which, trying to patch his wound, hit a nerve node. A rookie mistake. A fatal mistake.
"It was an accident," Sage's voice trembled. She stood five steps away, clutching her hands to her chest as if trying to hold back her own heart. "Viper, I swear, I tried…"

• Shut up.
  Viper's words sounded like poison spilled on glass. She turned slowly, and Sage saw her own reflection in the gas mask's lens—frightened, pitiful.
  Three months have passed since then. Three months of icy silence, broken only by the hiss of chemicals and the sound of Viper's footsteps, who always chose the opposite end of the corridor.
  Sage left her food at the door. Viper stepped over her.
  She wrote letters. Viper burned them without reading them.
  One night, in the lab, Sage found Viper asleep at her desk. An unfinished drawing—a joint project between her and Chamber—lay nearby. Sage carefully draped a blanket over her shoulders.
  Viper woke up instantly, her hand squeezing Sage's throat with a force she hadn't expected.
  "You have no right to touch me," Viper hissed. "You took everything from me."
  “I know,” Sage breathed out, feeling the darkness in her eyes. “And I’ll give you my life. Whenever you want. But first… let me just be here. Let me hate myself with you.”
  Viper stared at her for a long minute. Then she let go and turned to the wall.
• Get out.
  But as Sage staggered out, she heard a quiet:
  — Tomorrow. Bring some coffee. Chamber liked it with cinnamon.
  Sage froze, swallowing back tears.
  “With cinnamon,” she echoed.
  Viper didn't turn around, but the blanket remained on her shoulders.