Fever can support the immune system's attempt to gain advantage over infectious agents, such as viruses and bacteria, and it makes the body less favorable as a host for replicating viruses and bacteria, which are temperature sensitive. Infectious agents are not the only causes of fever, however.
Your sister's grandson is your great nephew. You are his great aunt (if you are a woman) or his great uncle (if you are a man).
Brenna D'Amico. Jane is a character in the movie Descendants, played by Brenna D' Amico. She is the daughter of the Fairy Godmother, and is known to be shy and insecure, but is fascinated with magic, even if her mother doesn't let her use it. She is portrayed by Brenna D'Amico.