Eric's Suspicion is a sub route in Adventure High.
Like the name implies, it's about Eric suspecting that Erin might not be her normal self right now.
Note that this is just a general outline for the route. It is not a walkthrough.
To start this route, you have to enslave Erin and changer her into any non-normal personality, then take on a request from the Monster Ranch. While he reacts a little to her country form, it's not very noticeable.
After completing the fourth monster quest while Erin is either Mindless or in Dragon form, she will speak to the Protagonist in the streets and ask for help.
If the Protagonist agrees to help her out, the Protagonist can either enslave Eric by casting Flirt and Suppression or by speaking to Julia to get some intel on Eric.
She reveals that Eric is easily flustered, allowing the Protagonist to cast Flirt followed by Shrink that leads to a unique scene.
Failing to enslave Eric locks the Protagonist out of the Monster Ranch, presumably permanently.