Some actors in the superhero world, whether intentionally or not, have received a bad reputation for leaking major spoilers. Yes, we're looking at you, Mark Ruffalo. While his bombshell was very blunt, some actor leaks are more low-key and can pretty much go unnoticed for a long time.
One of these possible leaks came from Karen Gillan, who plays Nebula in the Guardians of the Galaxy films, as well as in Avengers: Infinity War.

Last year, Gillan sat for an interview with Fandango, during which she revealed her character Nebula has a best friend in Infinity War, although she didn't reveal any names.
So @karengillan says Nebula has a new BFF in #AvengersInfinityWar & that it's a brilliant choice. Any hints @JamesGunn?? pic.twitter.com/TFk266k1DT
— Erik Davis (@ErikDavis) August 7, 2017
We didn't exactly see much BFF behavior from Nebula toward anyone in Infinity War, so now there's speculation maybe Gillan was giving us a tease about what's in store for her character in Avengers 4.