Just a few questions, @cheekyp :
He's 24. Does he live independently, is competent at budgeting, household chores, leaving the house independently?
Does he have friends? Does he keep his friendships? Do they invite him out and/or plan things together?
Does he have a job and/or is he happily or meaningfully engaged with whatever he's doing with his life right now?
Does he have plans, ambitions, or even just realistic desires for the future (e.g. his own home, nice holidays, car, etc.)?
Does he truly intimidate you (i.e. he frightens you), or is this an aspect of his communication you'd feel happy to discuss with him?
Talk to him about what he is doing, how it makes you feel, and what you'd prefer him to do instead.