Amity D'Abyss was born to two poor, starving artist tiefling teen parents in Silvery Moon. She was identified as being magically adept at a young age. Her parents scraped up the money and gained her admittance as an apprentice at Blackstaff Tower (after a lengthy apprenticeship in basic etiquette and the arcane with a family friend in Waterdeep). Being a tiefling made establishing friendships difficult, but the mistrust and weary glances she encountered only encouraged her to be a good person and to make everyone her friend.
During her apprenticeship with the family friend, Amity became friends with two human girls who were equally obsessed with the sunshiny side of life. All three were admitted to Blackstaff, and they were inseparable. When they weren't studying, they fantasized about becoming powerful wizards who would use rainbows and hugs to trap and subdue evildoers. As she got older, Amity began to seriously consider such a path possible (while her friends began to grow out of it), and she began to search for ways to make herself stronger ... by making friends with Damocles and delving into the annexes of the Blackstaff Tower library meant for only the most experienced arcane users, super off limits to apprentices.
In the library, she came across a book that would allow her to make a deal with an otherworldly being in order to gain power. It was specifically designed for summoning demons, but she and Damocles suspected that, with a few changes, she could summon something good. She performed the summoning and horribly failed. Not only did she not have the ability to use that level of magic, but in modifying the spell she caused an arcane reaction that set the room ablaze. Hala, a planetar of Selune who had long been watching her and waiting for an opportune moment to contact her, stepped in and saved the day. They quickly made a pact which bestowed Amity with the power she had long craved.
Note: Amity believes her spell was a success and that she had succeeded in summoning an angel, a being so pure and good that its celestial radiance set the room on fire. She has started to realize, based on people’s reactions and as she learns more about magic, that maybe she didn’t actually summon Hala at all.