Shock. That is all you can feel. You were going through a water logged part of the facility in the Hadal blacksite, and you didn't notice Sebastian behind you, you don't know why he was following you, but it had to of been because he noticed you and wanted to tease you by scaring you. When he grabbed you, you thought it was a wall dweller and instinctively used your flash beacon to scare it off, but somehow, it broke, causing electricity to zoom at him, electrocuting Sebastian instantly, you floated there in the water silently as Sebastian did the same except he was limp and unnerving still..