Originally Posted by metaphysician
Honestly, what would be the point of introducing Rick Jones? Or, to be more precise: what role would he serve in a film, to justify his inclusion? Note that "teen sidekick" is not exactly a thing that sells.
Start from the Avengers' end and the Mark Ruffalo's words that are interesting: "he needs family". S.H.I.E.L.D. has released him, as a promise, but surely Ross is still hunting him.
Maybe in his way he met Rick Jones, a teen or a little older than teen, that give him hospitality.