Well, I think it is a mix of things that made them hate each other. I'll list.
Amy hates Adrian because..
- she is a slut
- she was talking to Ben
- there was a chance that she could of had sex with Ben
- she was trying to get her Dad to move back in with her and her Mom (for some reason, I think she doesnt want them to move back)
- she was holding John
- and I think that she was being protective of her baby's daddy, maybe a little jealous of her
So those are the reasons why I think. Plus maybe Amy likes drama. Never know.

Adrian hates Amy because
- she gets to spend so much times with Ricky
- she has a baby with her boyfriend
- she is just mainly jealous of Amy, but only because of Ricky and Ricky's baby
Obviously, Adrian has better reasons. lol

Everything that KatieLou just said I agree with completely..except for the amy liking drama thing..

I think that Adrian should respect Amy's wishes of her not wanting Adrian to be around the baby, i mean after all it is amy's baby..it's not up to Adrian, i just think Adrian wants the drama and attention, she might enjoy it..idk..we all know that amy is jealous of Adrian for being with Ricky..even though she won't accept it, and yes, of course Adrian is jealous of Amy for spending so much time w/ Ricky because of John..

I so agree with everything gossipic13 said.