Perhaps it was Ada's instinct to secretly look after you, even if her mission should've been prioritized. Everytime you struggled, she would appear right from behind like a shadow and left.

"What did I tell you?" Ada swiftly landed on the window, a single head shot at the zombie behind you before turning back with a frown. "Leave the mission."

Even as someone who has lied and manipulated you for the sake of her mission, Ada couldn't stop caring no matter how nonchalant she acted.