Some cats like meaty treats, and if the son secretly fed the cat treats, the cat would likely pay more attention to the kid. I had a cat that behaved that way.
Is the 11-year-old already well-versed in cat-ology?
If not, teaching him cat body language could go a long way (plenty of vids on YouTube). Kids who aren’t too familiar with cats can accidentally over-stimulate/over-pet/over-engage them and stress them out without meaning to. Learning to pick up on airplane ears and tail flickering, etc., can help the cat feel safer, as well as things like responding to bunting, gentle rubs on their scent glands, etc.
And yes, also giving them treats, finding toys that they like and playing with them when the cat wants to (not when the kid wants to), etc. Laser pointers and springs are fun to try.
Explain to the boy that the cat is going to be a cat, and will choose. You can bribe him with treats, and he’ll remember that, but he won’t become your best bud because you “treat” him. He’ll become more loyal than a politician (for some value of “loyal”) but he’ll still be a cat.
Do I sound anti-cat? In the fifty-five years that I’ve had (for some value of “had”) cats, upwards of thirty in total, I’ve developed a pretty good understanding of the relationship. My last old cat died at the end of summer, and I decided that that was really the end. I’ve always thought that I was pretty good at living alone, but I was never really “alone”, there was always a cat. So after a couple of months, at the urging of a friend who understands me, I liberated Bunkie from the local shelter. He’s my pal because there’s only me, and if he had a choice, who knows?
Who cares? He pays attention to me for half the day, and ends the day sleeping pressed up against me. Every morning I start the coffee-maker, then cater to his needs. We have a deal.
Time for the boy to learn that we don[‘t always get what we want, but that if he’s a good kid, the cat will respond.
The first thing to do, and it may already be too late, is to never hurt or tease the cat. Once that happens there is no going back. Its a cat and it has a long memory of offenses that people have inflicted upon it.
Tell him that if he’s a good kid and learns to speak some Cat, the cat will probably respond. But the cat is a cat and will make its own decisions, some of them based on things humans don’t understand.
ETA: how to say “I’m friendly” to a cat: look straight at the cat for only a very brief moment; then close your eyes in a long slow blink and turn your head a little bit sideways. I think this means a combination of “I’m not afraid you’re about to attack me, so I’m willing to take my eyes off you” and “I’m not going to attack you, so I don’t need to be looking at you, but I know that you’re there.”
And don’t approach the cat directly; let the cat come to you, and don’t grab hold of it when it does. This part is often hard for a child.
When I was a teenager and had a date with a girl that had a cat I would rub fresh catnip on my pants leg.
Laugh all you want. It worked
The cat would do the figure 8 on me, jump up on me, and be super friendly. Girl would be delighted her otherwise aloof cat liked me so much. I just didn’t rub so much on that she could smell it.
Doing it enough times got the cat conditioned to like me even if I didn’t have the catnip on.
It’s mostly about who does the feeding. If the kid is the one putting the bowl down every morning, the cat will start associating him with the good stuff pretty quickly. I noticed with my own cat that she always follows the person with the treats. Just have him be the primary caregiver for a bit.
Cats love me. Lord knows why because I’m a dog person. I ignore them unless they approach me so maybe that’s the technique. There are countless times that I’ve been to a house and people have been surprised how often the shy cat takes to me. Of course I give them attention when they come up to or jump on me.
I lived in a house with housemates and my dog and two other dogs and a big grey cat that was very doglike. That cat adored me. He’d jump in my lap and kneed on my leg which is apparently a sign of great affection. Me and only me. The less that housemate and I got along it would infuriate her more and more.
Many kittens, and some adult cats, aren’t much interested in catnip.
Some dogs are, though.
There’s a lot of Cat that humans can’t speak, because it’s said with the tail (which we haven’t got at all), or with the ears (which we don’t have enough outer parts of to move properly), or even by raising the fur. But we can learn to understand quite a bit of it.
And some of it we can speak. I gave an example a bit upthread.
Dogs usually try to learn Human. But cats expect the humans to learn Cat.
Teach him cat body language. Teach him to learn signs a cat likes him, or the proper ways to pet a cat.
Also if possible put him in charge of feeding the cat. Feeding a cat is a good way to make them like you.
When a cat makes a slow blink, or closes its eyes while looking at you, it shows it trusts you. Its saying it feels safe closing its eyes because it doesn’t expect you to hurt it. If you slowly blink back or close your eyes in return, you are letting the cat know that you trust it too. You can communicate with cats by doing stuff like this.
Also if a cat presents its stomach, its not asking you to touch its stomach. Its just showing it feels safe being vulnerable. Most cats dont’ want their stomach touched even if they present their stomach.