The background story for Nebula is that she comes from a line of witches, specifically her Grandmother was a notorious Witch/Pirate Captain. Her Mother turned away from the gift for the axe. Here is the classic Crone, Mother, Maiden set-up and they are kind of all in her head, which is one reason she is crazy.
Nebula herself grew up a supposed orphan, which lead to failed-poacher, failed-archer, okay-bard. It was as a poacher she was told at some village fair that she had talent and should seek out the Conjurers in Gridania. However, instead she got hitched up into the Archers guild. It was only when she was kicked out and her power started to materialise that she finally joined the Conjurers.
[edit - I came up with this story back in beta when Bard would require conjurer as a class. This was changed in the game but I continued anyhow]Â
She is a terrible student, and they pushed her off to the Sylphs, where she met her Witch mentor, Kraggy Nel. Under her witch training she was sent to learn the basics of how magic is done throughout Eorzea. She enrolled in the various magic guilds to achieve this, again she is a terrible student.
This broad grounding in the basics and variety enables the Witchcraft training that is more about intent and conviction than dogmatic methods. Throw in some alchemy and gemsmithing and she is set for potions, charms, magic of a hedge witch and  more.
Now she is off seeking out some lost Sharlayan Witch to continue her journey into high Order Witchcraft (you can guess this ends up at Matoya, though there is a quest(s) to do to get there).
Nebula herself grew up a supposed orphan, which lead to failed-poacher, failed-archer, okay-bard. It was as a poacher she was told at some village fair that she had talent and should seek out the Conjurers in Gridania. However, instead she got hitched up into the Archers guild. It was only when she was kicked out and her power started to materialise that she finally joined the Conjurers.
[edit - I came up with this story back in beta when Bard would require conjurer as a class. This was changed in the game but I continued anyhow]Â
She is a terrible student, and they pushed her off to the Sylphs, where she met her Witch mentor, Kraggy Nel. Under her witch training she was sent to learn the basics of how magic is done throughout Eorzea. She enrolled in the various magic guilds to achieve this, again she is a terrible student.
This broad grounding in the basics and variety enables the Witchcraft training that is more about intent and conviction than dogmatic methods. Throw in some alchemy and gemsmithing and she is set for potions, charms, magic of a hedge witch and  more.
Now she is off seeking out some lost Sharlayan Witch to continue her journey into high Order Witchcraft (you can guess this ends up at Matoya, though there is a quest(s) to do to get there).
Char:Â [Nebula Stardancer] Â FC: [East Eerie Trading Co]
Link Shells: [Hugs & Cakes] Â [Witches' Wyrd Web]