Lethal Species by Megalomaniac2 is a crossover between Buffy the Vampire Slayer and the Alien series, set mid-way through Season Four of Buffy. When a xenomorph egg lands in Sunnydale and is claimed by the Initiative, the situation swiftly escalates when another government-sponsored group takes over analysis of the resulting alien.
Lethal Species contains examples of:
- Artistic License Biology:
- Xenomorphs can hatch from demons just as they can hatch from humans (although the resulting aliens will be slightly different from the standard version), and at least one hatches from a vampire despite a vampire being incapable of sustaining life normally.
- Rather than hatching as a Queen from the beginning, the first xenomorph to arrive on Earth goes through a period of metamorphosis where it creates a cocoon for itself so that it can transform into a Queen.
- Body Horror: Various examples of this, considering how the Xenomorphs hatch, but a particularly brutal example occurs when Spike is impregnated by a facehugger; while his vampire state allows him to survive the birth, he is described as walking around with a gaping hole in his chest for the next day or so until he can acquire enough blood to heal himself.
- Foreshadowing: Traetens belief that his companys lawyers would allow him to sue the Initiative (thus essentially suing the United States government) makes it almost obvious that the lawyers in question are Wolfram & Hart.
- Offing the Offspring: Spike may be the only person in the Alien franchise in a position to do this to the xenomorph that hatched from him.
- Sequel Hook: The fic ends with the last xenomorph egg being sent to Wolfram & Hart, creating the possibility that Angel will have to face the Xenomorphs at some point.
- Sherlock Scan: After Willow is abducted in a manner intended to suggest a xenomorph attack, Giles is able to quickly note the flaws in that scenario, as the clues suggest that the xenomorph broke into Willows dorm room by breaking down her door from the interior corridor, when it would have been far easier for it to climb into the building via the outside window.
- Underestimating Badassery: Traeten falls victim to this, with Willow explicitly musing that he has little respect for the Scoobies and the Initiative as intelligent people even if he complimented their abilities, allowing Buffy and Giles to see through Traetens attempt to create the impression that Willow was captured by the aliens and taken to their hive when she was caught hacking his databases.