Military Brat: Saito, along with his brother and sister, Ben and Megumi
No Sympathy: Louise has none for Saito, especially since she ripped him from his home.
In canon, Kirche used her familiar to drag Saito to her bedroom, where she was awaiting to try and ravish him. When she does this in this timeline, Saito dodges and throws Flame out a several-story window. He then drags it back up to her room, kicks down the door, and tells her that if she tries that again, he will kill her and the familiar, not even noticing her charms. Granted, it's because he thinks she was trying to assassinate him after having already survived several attempts... but still!
Omniglot: Saito can speak English, Japanese and French.
Ordered Apology: Louise ineffectively orders Saito to apologize to Guiche in the middle of their deal. He refuses.
OC Stand In: Tropes Are Not Bad, as Saito is much more sympathetic and developed than canon Saito as he realizes something is seriously wrong with the situation and tries to rectify it.
Pet the Dog: Louise takes Saito to the infirmary and pays for a healer.
"The Reason You Suck" Speech: Saito tears Louise a new one, when she tries to stop him from leaving Tristain Academy. She's only stopping him because her reputation would go in the tubes if he leaves:
Saito: "I'm leaving because you ripped me out of my home, my family, my friends, my future, my life. I'm leaving because your terrible magic is twisting my mind, and wiping memories out of my head. Hell, you probably didn't even consider that I had a life before I got here. You are insensitive and self-centered. I'm leaving and nothing you do can stop me."
Technical Pacifist: Saito. He does walk around carrying a lot of guns (even a missile launcher!), but tries to avoid killing people.
Saito: Relax, I seriously doubt that I can piss someone off enough to start another fight.
6 hours later
"I, Roger Armagnac de Fézensaguet challenge you to a duel!"
Translator Microbes: Averted. Saito never needs the translation spell, since he already speaks French.
Tomato in the Mirror: Some time after Saito returns to Tristain Academy, Louise, Guiche and Kirche discuss on how his behavior is questionable, something that, given the arguments on the table, even the reader might agree on. He starts wondering to himself how he became that much of an asshole.
Yandere: Saito turns into one when he drinks a love potion, but subverted since every time Louise uses Dispel, he falls in love with someone different (Louise, Tabitha and Guiche, in that order).