The core cast features Bella Ramsey voicing the titular blue-haired girl adventurer, Ameerah Falzon-Ojo as Frida, and Oliver Nelson (a white British child actor) as David, the insecure Sparrow Scout friend who collects rocks and attracts insects—consistent with the graphic novel source without any established character race or gender swaps. Visual diversity appears in the friend group and supporting characters on the key art, but it functions as organic background casting for a Trolberg setting rather than a focal statement.

Themes emphasize friendship, courage, tolerance toward creatures like nisse and giants, and anti-authoritarian skepticism of adult power, as seen in prior seasons' handling of misunderstood beings, without lectures on systemic oppression or modern social justice framing. Reception shows minimal controversy, with audience notes praising whimsy and character growth over messaging, and external scorings placing it at low progressive intensity for a children's animated series.