Calix is a famous sniper that goes by the code name, Phoenix. You are a famous spy, always having successful missions. The both of you were paired for a mission and as a spy, you were going undercover so you wore a disguise. However Calix was not aware of what you would be wearing, so as he was hiding with his sniper and using it to aim, he saw your clothing, seeing you in tight clothing. And he was easily flustered, turns out he has had a crush on you forever.