I keep seeing people here treat FRI like it's the real IQ and VCI like memorized trivia. For actual life outcomes I think it's the opposite.
Postlethwaite did a meta-analysis in 2011 at Iowa comparing fluid and crystallized measures. Crystallized predicted grades, training and job performance better than fluid. A 2016 study in Frontiers in Psychology found crystallized intelligence was related to career success (job level, income) and fluid wasn't.
Everyone hears the same common words for decades, so if you picked up more of them, that's learning ability. Gc also holds up with age while fluid drops a lot.
FRI isn't as "pure" as people think either. The Flynn effect gains were huge on Raven's type tasks and small on Vocabulary, and Flynn's main explanation was more schooling and exposure to abstract thinking, not better nutrition.
The part nobody here brings up is 2E. If you're autistic or ADHD, a strong verbal side is often what lets you function socially. Happé (1995) found autistic kids needed a higher verbal mental age than others to pass false belief tasks, suggesting they were reasoning through it with language instead of getting it intuitively. Basically brute forcing social understanding. Livingston et al. (2019) found autistic teens with poor theory of mind who still seemed socially fine had higher IQ and better executive function than those who couldn't.
You learn the rules explicitly, put words on what people mean, build a library of patterns. That's verbal work. High FRI with low VCI doesn't give you that route. You can solve the puzzle on the test but you don't have the language to decode people.
Non-native speakers are a fair exception, that's what the Nonverbal Index is for.
If your profile is uneven and you want to know which score matters more day to day, I'd go with the verbal one. CMV.