There is a walk of silence of 20 yards from the waiting room to the room where I see patients, and in five months I've still not worked out how to fill it. "How's it going?", for example, is clearly wrong, especially for depressed patients. Sometimes I try to make a jovial comment about the fishtank outside the smoking room. Right now there is a man with his sleeves rolled up, fishing in the fishtank.

I wonder if I should say something. There is a notice next to the aquarium which reads: "Please do not interfere with the fishes." I look at Johan, my next punter, feeling like I should know what to do. He leans over to address the fisherman, indicating the staff on the front desk. "Why don't you go and ask them for some help?" he suggests. The fisherman nods seriously. "Yes. Thanks." He walks off.

"You should change that notice," Johan says, as aggressive as ever: "No matter how important your mission, do not interfere with the fishes."

Sometimes I feel Johan knows more about schizophrenia than I ever will. What worries me is that he seems to have made a lifestyle option out of it. We sit down. "Before you ask," he says, "I haven't taken any of your filthy drugs, nor do I plan to, so can we please desist from this farce with the prescription pad at the end?"

Now to an extent, I respect this stance. There is something faintly depressing about depot clinic, where you review all the strangely cowed chronic schizophrenics who have been coming in for their monthly needle for 10 years, and sit at home all day smoking for a living.

But it's more complicated than it looks. Those chronic schizophrenics you see on the street, doing nothing but smoking and staring: that's not the side effects of the drugs we give them; that's the natural course of the illness. For the most part, they're the ones we missed 20 years ago. That's what I'm trying to avoid with Johan. And he is - although it's a cardinal sin to have one - pretty much my favourite punter.

The longest I've managed to get him taking antipsychotics for is a week, when the voices were getting too much. I'd also managed to convince him that I could find him a drug that shouldn't make him tired. "They're shit, they made me sleepy. I flushed them down the toilet." The game was up.

"Michael, don't expect me to fit into one of your little pigeonholes, because I won't. I'm not mad, and you know you can't section me."

But I don't want to section him. Well, that's not quite true. The first two times I met him he scared the shit out of me and I whinged at my slack locum consultant down the phone. But Johan presents no risks, and the worst that can happen is deterioration over the years. And Dr Slack, on his billionaire's locum consultant contract, will do anything to avoid admitting patients to the ward.

"Johan," I tell him, "I'm not going to section you. It doesn't matter what you call it: people who hear voices, have delusions, and think MI5 are spying on them (when clearly they're not, by the way) do better on medication in the long run. No matter what you call them." "God, you're all so fucking feeble-minded. You just can't cope with anyone who's different. Can you?"

"Look, I'm not your parent, or your teacher. There is no gain for me in you taking these drugs. It makes no odds to me either way - it's just you I'm worried about." He roars with laughter and gets up. "One day you'll learn." He's gone.