Starfox is actually Thanos' brother, though he has a very different history to his sibling. Born on Titan, just like his brother, Starfox grew up to be a fun-loving, carefree womaniser who thrived on adventure, whereas Thanos became a megalomaniac and nihilistic madman. Starfox finally began to take life a little more seriously when Thanos first launched an assault on Titan and, since then, he has had a number of conflicts with his brother - something which could easily be mentioned in a movie. In fact, when Thanos got his hands on the Infinity Gauntlet, one of the first things he did was commandeer Starfox and make him watch as he tortured, conquered and destroyed everything his path. He attempted to use one of his powers - the ability to manipulate others with his charm (he also has superhuman physical attributes) - to talk Thanos out of his plans, but he had his mouth sealed shut as a result. Something like this in the movie would be cool, and Starfox could then aid the Avengers - with whom he has connections in the comic books - in the final assault on his all-powerful brother. A turbulent future relationship with She-Hulk could then be on the cards in the Marvel Cinematic Universe, just like in the comic books.
