Spook
Christina calmly walked through the halls of the house, where a YIRAAAS agent had just been sitting down to dinner with his family. Shotgun shells clattered around her feet as she shot the agent in question, his wife screaming and the teenagers at the table sitting frozen as the body of their father slowly slid down a little, blood sprayed out in an abstract pattern on the wall.
Christina tilted her head slightly, shades hiding her eyes from their sight, until she levered them off her head. She had black holes for eyes. No pupil, no iris, just solid black straight across. The girl in a pink baby tee and jeans choked back a terrified sob. Christina smiled slightly. "Now...one Agent. Check. Pleased to meet you all. Name's Spook."
"You should be dead!" The mother said in a terrified voice. "Greg said Tanya-"
"Ah, Tanya. Sorry, that was the one mistake per person that you just used up." A knife flowered in the mother's throat and she gurgled horribly then fell forward onto the dinner table. Blood flooded the white tablecloth and Christina casually sauntered up to it, before lifting an empty glass and pouring some wine from the bottle on the table. The eyes of the two teenagers followed her movements as she sipped at it, watching them just as carefully. "So...the question is...do I kill you? I am an alien hunter, after all."
"Please don't kill us," the girl gasped out. The boy tightened his hands into fists.
"Sometimes you havta do regrettable things," Christina said softly. "I don't think I can let you live. Reasonably speaking."
"We won't tell anyone! Swear!" The boy said.
"Ah, but you can't garuantee that you won't *think* it." Christina shook her head slightly, then calmly shot the two teens. She wiped the glass clean of her own prints and put it in the mother's hand. She then quietly left the house, for the YIRAAAS to find, a small square of paper pinned to the front door with a thumb tack.
An omega symbol written in the family's blood.