Affection is a semi-hidden stat in Adventure High. It shows what a person thinks of the Protagonist.
From highest to lowest, it goes:
3 hearts (in love). At present time, no one starts with this.
1 heart (crush). Valerie and Erin are the only ones at present who starts with this.
Angry waves (don't care). Ms. Rack, Jane, Molly, Dr. Tiff and Eric all start at this level.
Middle finger (hate). Everyone else starts with this.
There's a few ways of increasing Affection at the moment:
With anyone except Molly, give them Love Potions. In Molly's case, it'll lower her affection towards you.
To increase Molly's affection, send people ink bombs. It'll make them hate you, but it'll increase Molly's affection in return, as she loves practical jokes.
Agree with the person you're talking to, or encourage them.
If Cassandra is your mistress, healing her during battle increases affection but ignoring her decreases affection again.