Really interesting insights, everyone!
Lin, thanks for your poetic and insightful deliniation of Neptune as "trickster". Yet I think Steven Forrest is right: no planet is in our charts just to hurt us.
Interesting to think about Pluto as the "antidote" to Neptune. Pluto deals with ruthless honesty, but the Neptune/Pluto sextile is so common that it is hard to know what to make of these planets' relationship. I would have suggested that Saturn is the antidote to a dysfunctional Neptune. I no longer think of Saturn as a malefic, but as Dr. Reality Check. But maybe a lot depends upon the individual chart.
Sundance, I have Neptune in the first house, which I have read about, correctly in my case, as conferring a kind of life-long identity crisis. But the older I get, the less troublesome this becomes, whether due to more life experience or a more outer-directed focus, I am not sure. Neptune squares Jupiter in my 4th, so I sometimes think my luck dissolves, but actually, I think I have had an OK life, all and all. So I see this aspect as indicating biting off more than I can chew--thinking I can do more (Jupiter=expansion) than I really can or will. Arguably Neptune makes a couple of very wide trines in my chart, but others would see themn as out-of-orb. In terms of drugs or alcohol, I don't do the former; and we have wine with dinner. So I don't see Neptune as quite so wretched in my life. Thankfully, he's left my 2nd house relatively stable.
In conventional astrology, Jupiter rules conventional religion and theology; Saturn rules ecclesiastical authority, and Neptune rules mysticism--but of the other-worldly variety. I think it is all too rare to find religious, spiritual, or mystical people who don't try to isolate themselves from society, but who plunge themselves into the real world, warts and all. But that was surely the message of Jesus and the goal of some faith-based organizations today.
freedomlover, it is hard for me to see alcoholism in your friend's chart. Neptunian, sure, with that wide Neptune/Mercury/sun conjunction. But Neptune really isn't badly aspected. One thing I note is that you used Regiomontanus houses: and in any of the common house systems except whole-sign and equal house, as you know, one can get intercepted and duplicate houses. I find the problem of intercepted houses really interesting. The first thing I looked for was the house that Neptune rules, but he's got Pisces intercepted. Then, of course, his Pluto/NN/PofF in Virgo in the 9th are intercepted as well. These can be entities in his life that just don't get a lot of "traction."
People drink for different reasons. Alcoholism is an addiction, so once people start for whatever reason, they may be unable to stop without a fairly fairly serious intervention like a residential treatment program. Has your friend ever said why he drinks?
With Uranus square sun, he may drink just to relieve the pressure.
I am not at all intuitive r psychic--but I just happened to wonder. If your friend is, indeed, an old soul, could it be that he has a kind of mission or destiny that frightens him, and that he tries to ignore by drinking?