What Did Cain seek to Accomplish?
I really can't pin down what Cain felt he was accomplishing by killing Abel. God had rejected his sacrifice and Cain was angered. Killing Abel would not change that rejection into acceptance. In fact it would obviously increase the rejection since he was warned before he killed Cain to change his attitude. If indeed Adam and Eve were more pleased with Abel as well, killing him wasn't going to change their opinion. As in God's case it would make it worse. So the only reason I can imagine is that he considered Cain a reminder of his inadequacy and decided to get rid of that constant reminder.
I also have difficulty understanding why Cain didn't fear how God might punish him. He was aware of the cherubim guarding the way to the tree of life and of Adam and Eves banishment from Eden. So he knew God would definitely react. Yet he plowed right ahead!
Opinions are appreciated.