I want my old sister back

Jack and Elsa Frost are in high school with their friends, Hiccup, Merida, Rapunzel, and Flynn. Elsa ran away from home after her brother, Jack Frost, found out that she had powers. Those two used to be really close before Anna and their parents died. Jack didn't know about Anna for a very long time. Jack used to be in a coma. He was in a coma when Anna died. But when Elsa comes back, she isn't the Elsa, Jack knows. Elsa is keeping this one secret she can't tell anyone to herself. But it finally comes out when she ends up in the hospital. The doctors finally told Jack what she has been keeping to herself. But when the other Guardians finally get back to their message, things just get worse. Pitch is back. But now he is not alone.