I was putting a slice of lemon in my tea and it reminded me of a bizarre conversation we had once. See, I am a lazy so-and-so, so I buy those jars of sliced lemons and just fish one out as necessary to pop in my tea. An indulgence, but it does save having half a lemon go mouldy when I don’t drink as much tea as usual.

One night when he was here, I offered him a slice of lemon in his mug of hot water. He acted as if lemons in a jar were some incredible innovation that he’d never seen before in his entire life. I suggested that every pub and bar in the country has a jar of them behind the bar, but he no longer frequents bars, didn’t look very hard when he did, and wouldn’t let it stop him treating it as outlandish if he had.

This is not much in itself but it’s yet another petty annoying dynamic that comes up again and again. If he hasn’t heard of something - even if it’s a perfectly common thing that he just never bothered to notice - he goes on and on about how strange it is and how does it work, or even gets annoyed at me for not intuiting the details he needs to know about it.

The most baffling example of this was when he told me the fact that Harry Potter was raised by Muggles was the sort of esoteric detail that only a dedicated fan who read the books intensely would remember, rather than a basic plot point with wide pop-cultural recognition. And then defended this notion by telling me that everyone takes something different from their reading experience.

Today is our child’s sixth birthday. For me, this means buying a present, making a cake, fielding calls from all the family members who want to know what a suitable present is, organising a trip to the cinema, explaining why not all presents arrive in the post on the day itself - basically being a parent.

For him, it means ringing me up, asking me what he should buy, asking me where he should buy it, sending a card in the post signed with his name and city, then ringing me up again on the day to ask how much the present should cost and what would be a suitable alternative present.

It hasn’t escaped my attention that I’m doing a disproportionate share of the work here.

The thing is, I don’t really care what he gets as a birthday present. My friends and family buy things that make my heart sink - things that make loud repetitive noises, or toys completely unsuited to a second floor flat without so much as a balcony - and I don’t complain. The important thing is that they’ve gone to the trouble of picking out a present they thought the littl’un might like.

Last year, his only involvement in the present buying process was to enter his PIN when prompted. This year, I suspect it will be a similar story. I’m counting the years until I can tell the kid, “Daddy didn’t buy you a present because he couldn’t work out how to do it without me holding his hand,” and let the fall-out go where it will.

He was telling me a story about a free kick in a football match a decade ago, which is pretty much par for the course for him. But he referred to the opposing goalkeeper as “that BASTARD”, which I couldn’t let go. See, that word has been banned in our household since he refused point-blank to put his name on the birth certificate. I know there’s not much stigma attached to being born out of wedlock any more, but it is an unpleasant word to describe my child, so no, not using it.

“I’m just pondering the way language evolves,” I said. “How a word that once mean an illegitimate child now apparently means a goalkeeper who makes a save against your team.”

He mumbled something that might have been an apology, then went on to talk about other words whose meanings he feels have evolved. “Riot” for instance. Apparently the riots earlier this year were actually “organised looting”, based on a newspaper article he read about a Waterstones that didn’t get a single window smashed despite being in the middle of a riot-affected area.

Also “anti-Semitic”. He trotted out the well-worn line about how the Palestinians are totally Semitic too, and I decided I’d had enough. I told him I had things to do, and suggested that he read a book or two to stop him being so aggressively ignorant. He was still demanding to be told what I meant when I put the phone down.

Five minutes later, it rang again. “What do you mean, ‘aggressively ignorant’?” No, sorry. I have neither the time nor the inclination to answer all his questions, especially since I know he’ll stick rigidly to his guns and try to tell me I’m wrong for some trollogical reason. I told him very firmly that I didn’t have time to discuss it and put the phone down. Again.

Transport is one of his special interests, and he loves to give me advice. Sometimes, it’s useful advice, like “If you want to go to Plainmoor, you want a train to Torre.” Sometimes, it’s marginally useful, like, “If you change at Birmingham and Cheltenham, you can save about five pounds compared to a through train.” And sometimes, it just leaves me boggling.

I was trying to get to Selhurst, and the simplest option seemed to be a bus from Elephant and Castle. “No, you don’t want to get a bus from Elephant and Castle,” he warned. I assumed he meant that it was a horrible interchange or something, but there really didn’t seem to be any other possibilities. “No, you really don’t want to get a bus from Elephant and Castle, because you will be the white person on it.”

Wait, what?

So I’m the only white person on a bus. So what? Am I supposed to be horribly unnerved by sharing public transport with people who have substantially more melanin than me? What are they going to do - try to touch my hair because they’ve never seen a white person before? I have absolutely no idea what he’s getting at here.

What makes it worse is that he knows that I once got on a Jubilee Line train that was packed with Millwall supporters. Millwall supporters do on occasion threaten opposition fans - especially if they happen to wear the same colours as West Ham - so that was actually a rather unnerving experience. Certainly a lot more frightening than being surrounded by nonwhite people. But it was the easiest way to get to my destination, so I just got on and tried not to stress.

This man, he eats jerk chicken and shops at the Halal shop. This man, he listens to World Music CDs. And this man, he thinks there is something self-evidently Bad about being the only white person on a bus. I don’t know what to think.

(The punchline is that one other person boarded the bus at Elephant and Castle. She was as lilywhite as me.)

His stated reason for never paying me any child support was that his former employers - now bankrupt - would discover he had fathered a child out of wedlock and attempt to constructively dismiss him. From what I heard about said employers, there’s a good chance this is at least partly true.

But when I claimed income support as a lone parent, I was obliged to notify the child support agency, so I filled in all the forms. They needed his employers’ address, and I only had their phone number, so I phoned and asked for their address. They gave me it, and only then thought to ask who I was and why I wanted it. I muttered “Oh, er, thanks,” and hung up.

Many months later, I told him what had happened. “Oh,” he said. “That’s how they knew.” Apparently, he had been chatting about his family with his boss or one of his colleagues, and they had taken for granted that he had a child. Somehow, the most reasonable way he could imagine for them to guess his terrible secret was from my completely unattributed phone call.

If someone phoned my business and asked for the address, I might think, “That was weird.” I might even think, “I hope that wasn’t the set-up for some sort of scam - I’d better be on my guard.” There is no way I would ever think, “One of my employees must have fathered a child out of wedlock.” Either he suspected his former employers of having quite a scary psychic talent, or he felt so guilty about keeping his child secret that he was sure anyone could guess it from the most tenuous of clues.

I love my child, and I’m glad that my child loves the man who provided the sperm to make him. But oh! that man drives me up the wall on a regular basis. Sometimes he’s borderline abusive. Sometimes he’s painfully stubborn. And sometimes he’s just so utterly bizarre I can’t even figure out what’s driving him.

Here’s hoping having a place to rant will help me get it out of my system and keep our relationship smooth, for our child’s sake.