Echo was a beautiful nymph, fond of the woods and hills, where
she had spent her childhood with other beautiful nymphs, to whom she was a loyal friend.  She was a favorite of
the queen, and attended her in the castle with complete devotion. She had the sweetest voice and the lightest feet. But Echo had one failing;she was fond of talking, and whether in chat or argument would always have the last word. 

One day the queen was seeking her husband, who,
she had reason to fear, was amusing himself among the nymphs.
Her fear was not ill-founded; for indeed, at the very moment the king was regaling himself among the beautiful nymphs secretly in the woods.
Echo, in accordance with her duties, accompanied the queen - assisting her in the quest for her husband. The queen was not familiar with the rough terrain of the woods, but this was Echo's home!
The lythe little nymph gracefully skipped over thickets and glided over crags, and very soon left the queen far behind.She was enjoying this game of hide and seek. Imagine her shock when she stumbled upon the king in the mango grove, with some of her very own childhood friends. Her shock soon gave way to fear as she realised that the queen was not too far behind. She knew the queen well - she was not known for her mercy. Surely, she would have her friends put to death if she found them with her husband. What was she to do?
Echo quickly doubled back to the queen and by her talk contrived to detain the goddess till the nymphs
made their escape. Talking was what she was good at; and this was the only weapon at her disposal. She talked of the woods and the hills - her home; the shimmering rivulet that flows by; and the color of the flowers when the moonlight caresses them.  She talked long enough to allow the nymphs to make their escape, but luck was not on her side. The queen discovered the last nymph making her escape, and realised all that had happened. In anger, she passed sentence
upon Echo in these words: "You shall forfeit the use of that
tongue with which you have cheated me, except for that one
purpose you are so fond of.  You shall still have the
last word, but no power to speak otherwise."
The queen was none other than the mighty godesses Juno, and her words, even when spoken in anger, were bound to take effect.
Echo was crestfallen. There was nowhere to go. She took her place among the hills and decided to spend the rest of her life there, in isolation.
One day, wandering among the hills, the nymph saw Narcissus, a beautiful youth, as he pursued the
chase upon the mountains.  She fell in love with him at first sight, and followed his footsteps.  Oh, how she longed to address him in the softest accents, and win him to converse, but it was not in her power. She waited with impatience for him to speak first, and had her answer ready.  One day the youth, being separated from his companions, shouted aloud, "Who's here?"  Echo replied, "Here."
Narcissus looked around, but seeing no one, called out, "Come out."
Echo answered, "Out."  As no one came, Narcissus called again,
"Who are you?"  Echo repeated the same question.  "Please come to me" said the youth.  The maid answered with all
her heart ,"Me" and hastened to the spot, ready to
throw her arms about his neck. 
He started back, exclaiming,
"Hands off, you freak of nature!  I would rather die than you should have me."  "Have me," said she; but it was all in vain.  He left her, and she went to hide her blushes in the recesses of the woods. It was now that she realised the extent of her queen's curse. From that time forth she lived in caves and among mountain cliffs.  Her form
faded with grief, till at last all her flesh shrank away.  Her
bones were changed into rocks, and there was nothing left of her
but her sweet voice.  With that she is still ready to reply to any one
who calls her, and keeps up her old habit of having the last
word.

~ from the myth of Echo and Narcissus