17 years ago - Natasha Irons is born.
5 years ago - 12-year-old Natasha helps her uncle John Henry Irons design and build his Steel armor.
1 year ago - 16-year-old Natasha inherits her uncle John Henry Irons's armor. She builds her own updated Steel armor, and unveils it when she, Miss Martian & Traci Thirteen save Superman from Metallo.
now - 17-year-old Natasha is invited to join the Justice Society by 32-year-old Karen Starr. She introduces her new teammate Jaime Reyes to her friend Traci Thirteen.
The decision to use Natasha Irons as our Steel came largely from our collective love of legacy characters. They're the strength of DC as a whole, and when the opportunity arose to use a legacy, even one as underutilized as Natasha, it seemed the thing to do.
Natasha has been featured throughout John Henry Irons's career, so much so that her eventual rise to superhero status seemed inevitable. She only appeared in her Steel armor a few times, however, before she was given a variety of different superpowers and used a series of largely forgettable aliases. It seemed bizarre that they were trying so hard to fix what clearly wasn't broken.
Natasha was never in the Justice Society, but our version of that team, especially under Power Girl, is deliberately focused on legacy characters, and it just seemed the perfect fit for Natasha.