Elliot had brought her hands back to her shirt and was holding it over her nose and mouth. She'd lost her jacket somewhere on the floor and could no longer see it. Her throat was starting to seize up and her lungs struggle for air. She was going to die here.
She could barely make out Tonks just a foot away and she reached out for the other woman. "To--" she started to yell but was cut off by a violent bout of coughing that doubled her over. She sucked in a breath but it felt like her lungs had frozen and all she could smell was the gas in the air. Her heart was beating so fast she thought it might explode in her chest as she struggled to get a breath in.
The lightheaded feeling that had been building intensified as she stepped towards the place where Tonks had been standing a moment ago, but was now a solid wall of gas. The world tilted and Elliot went down hard. She had a second to wonder why - Why Sid? Why her? Why Tonks? - before the world went black.