There really is not one solid headcanon on her, nor is there a real backstory to her. Though, she tends to follow this formula: batponies.wikia.com/wiki/Echo "Her personality is often portrayed as silly and playful, sometimes mischievous. A bit eccentric, but always upbeat and uplifting. She likes to eat a lot, especially really sweet and exotic fruits like lychee and mangoes. In more serious instances in stories of her appearance, she is usually a bit more assertive." No, I don't really care if you user her. I encourage all to include her in all kinds of work and art.