Maybe I sensed that Faith wasn’t carrying masses of tedious actual-person baggage; maybe that was why I liked her. Thinking about it now, all she did was reflect me back to myself. The person I liked more than I’m accustomed to liking my fellow human beings was me. If only an attractive man could endeavour to do the same, that would be ideal: work out exactly what I’d like to hear and then say only that, in between bouts of amazing sex. That’s a relationship that might work, unlike all my others.

I don’t get it, though. Faith’s come to the RGI to murder my grandmother – why strike up a conversation with me outside the hospital, try to ingratiate herself? Does it matter to her that the grandchildren of her victims should warm to her? Absurd.

Or perhaps it was a test: if she says things I’m bound to like and I fail to smile and agree, that proves there’s an impediment to my liking her – that might mean I noticed her sneaking into Marion’s room with a syringe in her hand.

It’s thinking about the timing of it that disturbs me most. How long before she stood outside the hospital, talking to me and smoking, did she inject poison into my grandmother? Ten minutes? Twenty? Did she wait until Drew and I had both left the ward, or did she sneak into Marion’s room while we were in the corridor arguing about catheters and bladder infections? Would we have noticed?

The conversation I willingly had with her about friends and dead houseplants would have reassured her that I suspected her of nothing.

Charlie says I shouldn’t assume she’s killed anyone. She asked the obvious question: if Faith Kendell is Billy Dead Mates, who was the man who gave me the little white book? ‘Maybe Billy is two people,’ Charlie said. I didn’t tell her I’d made the same suggestion to Simon Waterhouse and Chris Gibbs.

One, two, three, seven … I don’t care how many people Billy turns out to be. More than one murderer doesn’t interest me unless there’s more than one motive, and I don’t believe there is. It has to be something to do with pairs. At first it seemed to be pairs of best friends, but then Marion and I ruined it.

I have a theory I’ve not yet shared with Charlie. The labels we put on relationships often conceal the emotional truth. Marion and I were grandmother and granddaughter: a bond that ought to be close but wasn’t in our case. Could something similar have been true of Linzi Birrell and Rhian Douglas, and of Angela McCabe and Joshua Norbury? Did one of each pair grievously wrong the other, and did the other secretly never forgive them?

Thursday, 15 January 2015