Veronica was the first character introduced. She cares for her friends and people she likes and is (almost) always willing to defend them. She can forge notes well and wants to hang out with the Heathers (much like everyone else in their school). When reading the script, it really seems like the only normal character is Veronica. Everyone else just hates each other for who knows why, it's highschool. She is swooned by JD and his mysterious personality at a gas station and just.. falls in love with him after she sees him fight jock 1 and jock 2. She protects her best friend from getting bullied by the Heathers, and Chandler didn't really like that. The first person she goes to, is JD. She spends the night over his house and the next day she goes over to Chandlers house with JD. So JD is almost always by her side. Even after JD killed Chandler, she stayed. But after he killed Jock 1 and Jock 2. She broke up with him. She singlehandedly saved her whole school from JD trying to bomb the school. From reading the script, I can tell that Veronica is someone who loyal to her friends.
Chandler is the leader of the Heathers. She is an assertive, mean, bossy highschool girl. She is not afraid to speak her mind and put someone in their place. She is admired by almost everyone and everyone wants to hang out with her and the other Heathers, because they are the most popular girls in school. She's bossy over the other Heathers, and even after Veronica helps them out, she bosses her around too. She basically owns the school and everyone in it.
McNamara is one of the 3 Heathers (and my personal favorite). She seems like she has everything under control and that everything is fine, she's even playing into the mean girl role and being silly while doing it. But after Chandler dies, she kind of just loses that strength and courage, she even almost got peerpressured into ending her own life. Veronica thankfully stopped her from it though. She later became one of Veronicas close friends.
Duke is the 3rd Heather. Shes often seen getting shut down by Chandler for always speaking out before her. Its often shown that she wants to also be in Chandlers place. After Chandler dies, Duke takes Chandlers role, but she even almost makes McNamara end her own life.
Jason Dean, he's the main love interest. At first Jason Dean just seemed like a guy who was sad and empty and needed a woman to save him, but after he started killing people and threatened to bomb the school you see that he's kinda kooky and not in the best mental state. It shows that the main reason he's so out of his mind is because he watched his mom die in an explosion accident that was caused by his dad. So yeah traumatized crazy man alert.