The Asperger's Special Interest's Impact on Making and Keeping Friends

When I was younger, I didn't really "make friends". They made me. Come to think of it. Nothing has really changed. It's not that I'm an unfriendly person, it's just that I can never figure out the boundaries between friends and acquaintances. To me, people are just people and I generally respond to them how they respond to me. 
I don't think that I'd have any friends, only acquaintances, if people didn't persist in making friends with me - and  I'm very grateful for their friendship and support.

Bonding over Star Wars

When I was in primary school, I had a birthday party. My parents invited a small group of children and I remember having difficulty knowing who to invite. The list started off with the one friend that I actually had, plus any kids who had invited me to their parties at some point (bad luck if you didn't have a party).  From there, I think the group would have been all girls if my parents hadn't insisted otherwise. I was never any good at sports and I always found that girls, with their interest in just "talking" were more my style.

My Birthday Party in 1977. I'm the photogenic one with a cup on my face.

One of the presents I received at this party was a Luke Skywalker figurine.
All of the kids ooohed and ahhed over that figurine but at the time, I really had no idea what it was. I just knew from their reactions, that it was somehow special.
I took the figurine to school and one of the kids wanted to play with me. He brought his own figurines in and I started to learn the names of the characters and I eventually managed to get a couple more.
I didn't see the actual film until much later.  In fact, I know we were the last in our area to see it because they were removing the posters from the cinema when we walked out.
I think I played with this boy and his Star Wars figures at lunchtime at school for months. They were probably the happiest days of my primary school years. I continued to play with my Star Wars figures for years (and yes, I still have them but no... I no longer play with them).
After about three months of play, my new found friend suddenly started talking about trucks. I couldn't think of any trucks in Star Wars. Sure, there was that big Jawa thing but that was it. I think I mostly ignored the conversation for a couple of days and just continued playing with Star Wars figures. In the meantime, my friend stopped bringing in his Star Wars figures and started bringing trucks. I never brought any trucks in. I don't even know if I had any or not.
Eventually, the disconnect was significant enough that my new-found friend wandered off to play with other kids who liked trucks and I was left to myself again. I kept bringing my figures in for a week or two but he never came back and I couldn't be bothered getting them out to play by myself.
I really missed him when he was gone and I remember trying to work out how to get my friend to come back. Sadly he left the school forever a few months later and that was that.

Learning to Change Conversational Channels

In my later years of high school, I ended up with a small group of devoted friends, at least some of whom were on the spectrum. Being older, they were able to convey their conversational issues. For example, we'd often get told "you guys just talk about computers all the time".
I honestly didn't pick up on this. Yes, we did talk about computers most of the time but saying that was like saying "hey, the sky is blue!".  I didn't realize that some of the members of my group were trying to tell us that they wanted to talk about other things.
Eventually my mother heard someone say it and when the kids were gone, she explained what the problem was. My mother was never one to give up and she continued to explain the problem weekly for what seemed like years.
It's not a bad thing because eventually I understood -- and more importantly, I understood in time to keep my friends. 
I started to try to monitor the conversations and when I realised that we were talking about computers for too long, I'd try to switch the conversation to something that everyone could participate in. We ended up with a fairly short list of topics; movies, TV, religion, computers, school and sex but it worked and it allowed the group to function without alienating people from the conversation.
More importantly, having to converse on other subjects broadened my horizons, enabling me to learn more about new subjects, find new interests and get on with people well into adulthood.

Parenting

Fast forward to the future and now, as a parent, I'm finding myself having to explain to my kids why they need to diversify the topics that they talk about. It's funny because I'm a fairly technical person with two tech-obsessed boys and you'd think we'd all be on the same wavelength.
We're not. I work with computers all day now and the last thing I want to talk about when I get home is computers. My eldest son seems to have a special interest in mobile phone technologies and he'll go on for hours if you let him about the latest phones, their operating systems and their technical capabilities. My youngest son finds this boring. He's into computers and will talk about motherboards, and gaming and the capabilities of various graphics cards.  It's amazing to me that their topics can be so similar and yet so "boring to each other".
I'm always trying to teach them to talk TO each other, not AT each other but it's harder than you'd expect to get the point across and to change these bad habits. 
We've found that as a family, doing things together, such as vacations, outings, watching movies and telling jokes around the table increases our common ground. It means that we have things that we can talk about that we can all relate to. 
I think the way forward for my kids and their friends is to increase the number of "common ground" activities that they're involved with and build up shared memories while at the same time, constantly reminding them to switch topics regularly and share the conversation with others.