Julian Assange moves like a hunted man. In a noisy Ethiopian restaurant in London’s rundown Paddington district, he pitches his voice barely above a whisper to foil the Western intelligence agencies he fears.

He demands that his dwindling number of loyalists use expensive encrypted cellphones and swaps his own as other men change shirts. He checks into hotels under false names, dyes his hair, sleeps on sofas and floors, and uses cash instead of credit cards, often borrowed from friends.

“By being determined to be on this path, and not to compromise, I’ve wound up in an extraordinary situation,” Mr. Assange said over lunch last Sunday, when he arrived sporting a woolen beanie and a wispy stubble and trailing a youthful entourage that included a filmmaker assigned to document any unpleasant surprises.