- "Thousands of years ago, these hunters found a backwater planet. They taught humans how to build and were worshipped as gods. Every hundred years the gods would return. And when they did, they would expect a sacrifice. Humans were used to breed the ultimate prey."
- ―Sebastian (from Alien vs. Predator)
Professor Sebastian De Rosa was an Italian archaeologist who took part in a Weyland Industries expedition to Bouvetøya, Antarctica in 2004 to investigate an ancient Pyramid buried beneath the ice there. The Pyramid was discovered to be a Yautja temple and hunting ground where the Predators would breed Xenomorphs for use in their Hunts, and the expedition soon became caught up in the battle between the two species.
Once a promising up-and-coming archaeologist, Sebastian found himself shunned by the wider scientific community following the publication of his first doctoral paper, which challenged established theories regarding the origins of ancient civilizations; chiefly, the notion that the Great Pyramid at Giza had been built by the Pharaoh Cheops. Determined to prove what he considered to be the unrealized truth, Sebastian published a second paper, based on his own translation of inscriptions found on the mysterious "Inventory Stela" recovered from the ruins of the Temple of Isis in Philae in the 1850s. In it, he proposed both the Great Pyramid and the Sphinx on the Giza Plateau in fact pre-dated Cheop's reign, and were constructed, not only long before the would-be Pharaoh was born, but before the ancient Egyptian civilization had even come into being. The pyramids were, he claimed, left over from an earlier, hitherto unknown ancient culture. The implications of this theory, if proven, would change recorded human history.
The reaction to this contentious paper was dramatic — the press widely misconstrued his theories, with one reporter producing the unfortunate headline "Archaeologist Claims People from Atlantis Built the Pyramid". Most of the established archaeological community ostracized him, and as a result Sebastian set himself on a quest to prove his theories. In 2003, this quest led him to the Temple of the Sun in Teotihuacan, Mexico where, in the 1960s, a peasant farmer had recovered a small gold coin inscribed with characters that resembled the earliest form of Egyptian hieroglyphics. Chemical dating techniques had subsequently revealed that the artifact had been made around 3000 BC — yet it had been found in a Mesoamerican city, thousands of miles across the ocean from the cradle of Egyptian civilization in the Nile Valley, long before any known culture existed in the rainforests of Central America. While the object had largely been dismissed as a forgery by established historians, Sebastian now hoped to "repeat the experiment" by finding another such object in Teotihuacan, and thereby prove his theories on ancient human civilizations pre-dating the accepted dates.
After eighteen months of digging at Teotihuacan, Sebastian and his team had made no significant breakthroughs. With his archaeological permit coming to an end, the minister who had granted it, Juan Ramirez, was growing increasingly impatient, as the excavations were holding up development of the site for tourism purposes. During a visit by Ramirez and his assistant Olga, Sebastian suffered yet another setback when a supposedly sealed tomb discovered on the site was found to have been looted long before the team arrived — Sebastian found nothing but a rusty Pepsi bottle cap inside. To add insult to injury, immediately afterwards Ramirez informed Sebastian and his assistant Thomas that he would not be renewing their dig permit, and that he would be replacing them with another team.
Sebastian saw a way to continue with the Mexican dig when Max Stafford offered him a large sum of money on behalf of Charles Bishop Weyland, in exchange for meeting with the billionaire and discussing a venture he proposed. Sebastian readily agreed, having no intention of joining Weyland's expedition, but hoping to use his money to continue the excavations at Teotihuacan. However, upon meeting the rest of the expedition members aboard the Piper Maru and learning of the mysterious pyramid discovered beneath the ice on Bouvet Island, Sebastian immediately realized the discovery could well prove his own radical theories and eagerly agreed to take part in the exploration of the structure.
Inside the pyramid
- "Only the chosen ones may enter."
- ―Sebastian, translating ancient hieroglyphics (from Alien vs. Predator)
Once the team reached the pyramid, Sebastian and Thomas immediately began translating the symbols found within, deciphering a little of its purpose. After the team was largely decimated by the awakened Xenomorphs and the Yautja hunting them, Sebastian and Lex found themselves to be the last human survivors. Deep within the structure, they encountered yet more hieroglyphs, which Sebastian was able to translate and reveal more about the Yautja's history with Earth, including the pyramid's use in their initiation hunting rituals. Armed with this new knowledge, Lex convinced Sebastian that they should return the Plasmacasters the team had taken to the Predators, reasoning that once they had them, the creatures would turn their attention to killing the Xenomorphs.
As the two survivors continued to search for a way out of the pyramid, Sebastian was snatched by Grid and dragged away to the Hive the Xenomorphs had constructed in the sacrificial chamber, where he was cocooned and implanted with a Chestburster. He was later found by Lex, after she allied herself with the remaining Yautja Scar, and he pleaded with her to kill him so that he may be spared the pain of the Chestburster's birth. She reluctantly complied, shooting him dead, but moments later the Chestburster erupted from Sebastian's corpse, only to be caught by Scar, who killed the infant Xenomorph by snapping its neck.
- In early drafts of the film's script, Sebastian was known as Sebastian Wells.
- According to author Marc Cerasini, one of the early drafts of the film didn't have Sebastian as an Italian yet.
- At one point, Lex asks Sebastian how to say "scared shitless" in Italian, and he responds, "Non vedo l'ora di uscire da questa piramide con te, perché mi sto cagando addosso." What this actually means is, "I can't wait to get out of this pyramid with you because I'm shitting myself."
- Sebastian's actor's (Raoul Bova) height is 5ft 11 ¼ (181 cm), so that is also how tall Sebastian would have been.
- Paul W. S. Anderson (writer and director). Alien vs. Predator (2004), 20th Century Fox [DVD].
- Marc Cerasini. Alien vs. Predator, p. 32 (2004), HarperEntertainment.
- Marc Cerasini. Alien vs. Predator, p. 38 (2004), HarperEntertainment.
- Marc Cerasini. Alien vs. Predator, p. 39 (2004), HarperEntertainment.
- Marc Cerasini. Alien vs. Predator, p. 37 (2004), HarperEntertainment.
- Marc Cerasini. Alien vs. Predator, p. 40 (2004), HarperEntertainment.
- Paul W. S. Anderson (writer and director). Alien vs. Predator Unrated Edition (2005), 20th Century Fox [DVD].
- Alien vs. Predator script (September 26, 2003 draft) by Paul W. S. Anderson
- "AVPGalaxy - Marc Cerasini Interview". Retrieved on 2017-10-20.