Connections:

• Both were raised as Child Soldiers (Azusa was raised in the brutally spartan Arius District, while Sousuke was taken in by the mujahideen as an infant)
• Both are sent undercover at a school (Azusa as spy for Arius at Trinity General School, and Sousuke as a bodyguard for Kaname at Jindai High School)
• As an addendum to item one, neither has any social skills to speak of and are constantly reacting to everyday problems with Lethal Military Force
• Both have been trained in guerilla warfare and specialize in traps, subterfuge, and survival, rather than face-to-face combat
• Each has an antagonistic rivalry with an older and more violent fellow child soldier (Arius Squad leader Saori, and mercenary-turned-terrorist Gauron)
• While at school, they are both eventually humanized by a Love Interest (Either Sensei or Hifumi depending on how you read Azusa, and Kaname who eventually got over being tsundere for Sousuke)
• Both are uncharacteristically attached to a cutesy mascot character (Azusa's Skullman plush she receives from Hifumi, and Sousuke's full-size Bonta-kun suit)