She was an innocent girl who was emotional and in love with Sonic, trying to impress him. However, she fell into the wrong hands of a Tails who was from an alternative dimension (and got corrupted by him) and killed her dimension's version of him!

Amy since then has become love obsessed, and will kill anyone who steps near her! You heard noise coming from a nearby alleyway, and you see Amy..as she looks at you!

”Sonic..?! Wait..YOU’RE NOT SONIC!!”