What if they were in our world?
I personally enjoy alternate universe fics (perhaps it's the Marvel fan in me!), and lately, I've been into Assassin's Creed (just finished the second game! Now I'm collecting feathers and glyphs...). So, of course I'm thinking about all the characters and how they would be in our world. ...well, our reality; technically, they're in the same world as us.
Altair I can imagine being some vigilante. I can't imagine him being anything other than an assassin, considering that he was brought up within the Order since he was a child. He'd be IRL Batman. But in white. And no bat motif. Maybe an Assassin symbol motif.
Malik would be his equivalent of Alfred the Butler. "But I just want to be a law student...!" "No, you're helping me be the hero this city deserves!"
Al-Mualim is the top dean of some university, filled with wisdom and knowledge, but secretly trying to take over the world! ...or he's some crazy, head librarian who feeds the pigeon's on his library's roof from time to time.
Desmond is a bartender and loving life, because he did not grow up on The Farm, and life is simple and good. ...UNTIL THE CRAZY LIBRARIAN FINDS HIM AND DOES EVIL EXPERIMENTS ON HIM! ...and then he eventually joins Assassin Man in the skies, defending Gotham/New York/wherever the heck they live from evil.
...I think I just conglomerated Vidic and Al-Mualim together. My bad. Vidic would probably be a mad scientist, or the Dean of Chemistry/Biology/Neuroscience at Al-Mualim's university. He's the one who would do all the actual kidnapping.
Omigosh, it would be Templar University! Adha would be forced to attend that school by her Templar parents, and that's where she meets her mild-mannered colleague, Altair. They meet in an Ancient Mythology course! It's perfect! (gasp) Altair could be Al-Mualim's Teacher's Assistant! And Malik would be his much more responsible and reserved classmate, down in the Law School section of campus.
Rebecca would also attend this school, in their Computer Science program! She could be part of the school's tech support, as an Assassin spy; she'd be fixing their computers, but also planting viruses and stealing files from the Templars!
I see Shaun as one of the Ancient History profs. Incredibly smart, thereby becoming a professor so young, but little does he know that the Templars intend to use his knowledge for evil.
Lucy is still a budding neuroscientist, or whatever she is, and Vidic gets her to work for him as an intern at their university. Vidic forces her to do crazy brain/memory-reading experiments, and she complies out of fear, until the whole Subject 16 fiasco. Then she meets the bartender and decides to try and contact the Assassins (Rebecca!) and escape (transfer to another school).
Leonardo da Vinci is Leonardo da Vinci. He gets to stay in his own time period and do fun, non-Assassin-related things, like paint the Mona Lisa.
Ezio, Rosa, and Antonio are all students! ...in college. They do not go to Templar University. They go to Venetia College, and they're all very happy there.
Rosa is bassist in her own death metal band, because she is a rock star like that. Antonio is her manager.
Ezio is the worst college student that ever walked the face of the earth. He does not attend class, he does not read. He doesn't even need to work, because his parents help manage one of the biggest bank companies in the country, and they are rich. All he does is pick up chicks. It bugs the heck out of Claudia, because their Uncle Mario is forcing her to work hard and become an accountant. The only reason Ezio stays enrolled in Venetia College, is because Caterina and Cristina attend the school. ...Also, Teodora and Paola are teachers there.
Eventually, though, after his father and brothers are gunned down by Templars for...some...reason, Ezio becomes the third Batman in the sky! Now our city is safer than ever! Also, Ezio, Altair and Desmond all set up a Batman Order with a Batman Creed, and they train Novice Batmans to work with the Assassins (Yes, the Assassins and Altair's Bat-crew are now separate organizations...this is what happens when all three of them exist at the same time.), and eventually the city is crawling with white-clad superheroes, and the crime rate is all but gone.
...Dude, I would totally go to Venetia College. Or join the Batman Order. Either or.