Echo was Hera's favorite nymph. One day Hera found out Echo has tricked her, therefore she banished her from her kingdom. She was devastated because of that.
Narcissus was separated from his group, he was wondering around. He heard a noise coming from the woods. Then, he started to hear yelling, so he followed the voice.
Narcissus was soon to see that Echo repeats his words, little did he know that it was the curse that Hera cursed upon her. He did not know though, so he would abuse her.
Narcissus saw the most beautiful person in the world, his reflection. He fell in love with it, he said "I love you" to his reflection, and Echo said it back thinking it was for her. Then, he jumped into the pond trying to grab his own reflection, soon Echo jumped, too.
Both Narcissus and Echo died by drowning. So, basically Echo and Narcissus died for something that they both could never have.
This story could help modern day kids because it teaches that they should not stay in a conflicting relationship.