Youth
Delta grew up in the general area of Inkopolis Square. Even before she got her humanoid form she'd fiddle with fake toys resembling weaponry, like splattershots or bombs alike. She'd intitally wish to be a turf/anarchy player, but really grew into the gear side of the battles instead after maintaining her squid/humanoid forms.
Early/Mid Teens
When she met Marie in the square, she instantly knew she'd want to participate in the Squidbeak Splatoon. She didn't think much on the team-building or world-and-Callie-saving aspects of it, more thinking about all the awesome overpowered gear she'd be allowed to practice with. Her and Sheldon become quick friends, the two of them together geeking out together and cooking up new weapon kits constantly causing Marie to silently resent the two. (Which Delta didn't respond too kindly too, which really stressed their relationship. Eventually they couldn't stand to have a casual conversation with eachother and kept it work-related.)
Late Teens
After the course of Splatoon 2's hero mode, Delta goes on a hiatus from the more rigourous agent work, rather becoming a specialist in her field and pairing up with Sheldon as a Ammo Knights employee. Here she not only drafts new weapons, alongside specials and kits, or doing boring stuff like working the shop when Sheldon is busy, but also works as a stunt dummy for promotional Ammo Knights content, testing out weapons or doing dangerous stunts with them for commericals and such. (The manuvers learned during her time with Squidbeak and general hardiness help with this)
