Home and Away star Charlie Clausen, who plays teacher Zac MacGuire, has been speaking about the difficulties his character will face in an upcoming storyline.

Warning: spoiler alert!

Fans will see a schoolgirl's crush on Zac turn into something darker.

Actor Clausen told TV Week: "He's not alarmed at first because it is teenage stuff. It is fairly innocent and harmless. It's that classic thing that she feels she is too mature for the other boys and Zac is a real man and she's more suited to him.

"He tries to be subtle but he can't ignore it. He tells her, 'I know what you are doing; it's inappropriate'."

Clausen added: "His first reaction is embarrassment, but she is clearly delusional because her interest in Zac is bordering on manic. She's convinced they are meant to be together.

"It just gets more complicated for Zac. Since he has come to Summer Bay, we thought that he could handle any situation, but this one he may have misjudged."