Seems we only really officially meet him in the Night City legend ending but if you keep an eye out you may see him in other locations keeping an eye on you in other quest lines, personally I have only seen him at the end of the quest with the Jeffersons and the people trying to brainwash and reprogram their minds but I have heard others say they have spotted him elsewhere. Anyone have any theories as to who he might be?
Now it could be a coincidence that he makes his appearance at the end of the quest with the Jeffersons but it is more likely a conscious choice to put him there indicating that he may have some involvement in the re-writing of the brains of the Jeffersons, it is also hinted at that he may be able to help V with their illness provided they do something for them in return, and considering that the illness killing V is related to the chip rewriting her DNA to better fit the the psyche of Johnny Silverhand it does not seem like a stretch that one who is able to reprogram the mind might be able to cure this illness too.
