Believe it or not; Juniper's age WAS sorta given in the show.
No I'm not kidding. But quick note;
Callahan is 5'11 per Baymax scan. Point?
Krei stood next to him and is roughly the same height; and although the wiki didn't have the exact frame of him standing with her, he stands next to Juniper in Big Hero 7; her height on full display. That's why I make her 5'9 in my Clan Kase series btw. Not cuz of this but cuz I could see she was very tall.
Anywho, you didn't come for Juniper's height; you came for me to explain why fanfic writers like me and @spyrkle4 are right when we write her as a teenager.
Well let's get the obvious out of the way of why people usually assume Juniper is a teen;
Her attitude (when she's bratty in anger to her mom in Big Hero 7 namely)
But let's actually get to what solidifies her as a teen/kid according to the show itself, one of @spyrkle4/Sparks' favorite eps; Something's Fishy
During what shouldn't have been their only musical number in the show, or their last important appearance (not counting their feral states up til City of Monsters), Barb sings something rather specific in 'We're Gonna Be Good'.
"I gave you everything through a larcenous childhood." Barb sang this to Juniper. Now let's run that by again; a larcenous childhood.
As in she robbed to provide for Juniper and possibly herself.
While I didn't discover this til after writing Clan Kase, it does support Juniper being at least 17, but there's a chance we can narrow that down to 15-16.
High Voltage didn't start crime dancing until Issue 188 (More or less occurs in March 2032 for those curious about the timeline). This was more or less their debut not only as dancing crooks, but seemingly crooks in general.
If we take this as literal as possible, it means that High Voltage started not only for fame to some extent (possibly), but for Barb to care for Juniper. In the same episode Juniper says she's never been to a school dance. But school dances depending are held as early as elementary/middle school; but it's possible Juniper had to drop out due to her family's financial situation before she had the chance to go to a dance.
And we can maybe narrow this down further with High Voltage's debut possibly hinting that they didn't turn to crime til recently, making Juniper 14-15 at the earliest with their situation getting even worse by the time of Issue 188 if we assume the chances of her getting a 9-11th grade dance are high.
One quick piece of info before we conclude; and it comes from Issue 188.
The car that was probably locked away in deep storage. But Sparks remembered it in Heroes of Flowers, so yay; forgotten lore returning :D
Anywho, I watched the ep after seeing that technically Juniper would be driving, however the wheel is on the RIGHT side from what I could tell. See; I timestamped it
It's possible Juniper isn't driving because she doesn't have a license yet. I might be wrong on that point, but it's still a possibility.
So what does the evidence say?
Juniper is a teenager, probably 16 at the oldest and definitely 14/15 at the youngest to keep it narrowed down/bias not letting me change it XD
15-16 might be more likely if we want to assume she was close to driving what I dub the High Voltage Mobile. Anywho, hope yall enjoyed this deep dive :D
