Yui and Suguha

After Kirito goes AFK to get some food, Leafa tries to investigate Kirito thinking that he was here to mess with her as part of some revenge plot. Only to come across Yui who sets the record straight that not only does Kirito not know that Leafa is actually his sister Suguha, but that Yui isn't going to condone anymore of Aunt Suguha bullying her Daddy.

Example of:
Extremely Protective Child