Don't ENABLE him
If he HAS to move back in you are going to have to set some very strict boundaries and if he crosses ANY of them, kick him out IMMEDIATELY!
Some suggestions:
1. NO STEALING.
2. Get a job. Set a time limit for this... (a month).
3. NO DRUGS or ALCOHOL.
4. Do your fair share (housework, yardwork etc.)
5. Above all else.... treat Mom and Dad with respect.
If he can't or won't agree to follow your rules, do not let him move back in.
Good Luck!