Cryptic Messages

When Warren Vidic and Lucy Stillman leave the building at the end of Assassin's Creed, Desmond Miles is able to use his Eagle Vision, much like Altaïr in the past. There are messages scribed all over the floor and walls of his room and the Animus Room. Subject 16, the patient before Desmond, wrote these with his own blood to warn Desmond of what is happening.

Other
'Quetzcoaltz' is probably a misspelling of Quetzalcoatl, the Aztec deity. Quetzalcoatl was the God of the sky and creation, and was responsible for the creation of books and calenders. Depicted as a feathered serpent, he was also the symbol of death and resurrection. Among the Aztecs, the name 'Quetzalcoatl' was also a priestly title.
 * I am the Alpha and the Omega, the Beginning and the End: This is referenced to in Desmond's room, with the '22.13' symbol, which is the appropriate passage in the Bible.
 * Explanation: This is a well-known phrase from the bible. It means that God is all-powerful. This yet again links back to the "New World Order" conspiracy.
 * 3.0.0.0.0. This is also written in Desmond's room.
 * Explanation: References the Mayan Long Count calender; the Mayan calender also ties in with the 2012 conspiracy.
 * In Desmond's room there are three more types of writing: Hebrew, Arabic and Chinese.
 * Explanation: Hebrew-עולם הבא: The writing in Hebrew means "The World to Come" (Afterlife).
 * Explanation: Arabic- الزلزال: The writing in Arabic means "The Earthquake" which is the 99th Sura of the Qu'ran and tells of Judgement Day and one of the signs of the end of the world.
 * Explanation: Asian Texts-Several quotes relating to the game and its key protagonists.
 * "You reap what you sow."
 * "One who wants to read into his future simply needs to write his own past."
 * "A man without far sight, must have near worries."
 * "Hearing is better than not hearing, observing is better than hearing, knowing is better than observing, and doing is better than knowing."
 * "As a human being, if you want to know the spiritual realm of Buddha, you have to observe, you have to know that everything you see in the world comes from your own mind."
 * Within Emperor Jiajing's sin and Quetzcoaltz's hunger lies the Answers.: A message in Desmond's bedroom.
 * Explanation: The Jiajing Emperor was Emperor of China from 1521 to 1567. He is known to be a cruel ruler, and an assassination attempt was made on him in 1542 when his concubines tried to strangle him while he slept (a plot that ultimately failed). He was also obsessed with collecting elixirs and artifacts, in the hope that they would grant him everlasting life -- this could possibly mean that within Assassin's Creed, he managed to acquire a Piece of Eden.