Ellis could hear voices echoing down the tunnel. [i]Fools![/i] He thought, as he flicked the safety off his sidearm. [i]They're so obvious![/i] But then, as he drew his pistol, he stopped himself. What if this wasn't an enemy attack? Should he call? Against his better judgement, he shouted, speakers lending fuzzy feedback to his voice. 
"You will halt where you are. If you continue to advance, you will be identified as hostile. You don't want to be hostile."
He raised his weapon, and focused, fortifying his barrier. The sight lit up a dull green, indicating a fresh heat sink.

The voices continued. Maybe they didn't hear him. It would be better, he decided, to start of passively, rather than armed and aggressive. He holstered his weapon, upped his external speaker volume and shouted, "HEY! IF YOU'RE FRIENDLY, YOU'D BETTER TELL ME NOW!"

He concentrated, readying his biotic powers in case he needed to fight, relishing the feeling of energy rushing through his body. His barrier flickered slightly, and sizzled when he put his side to the tunnel opening, hidden slightly behind a support girder. [i]Not the best cover, but it'll do.[/i] And he waited. Even as the orange light of approaching security drones grew brighter and brighter, he waited.