Character, rarely. Behaviors, yes. I think we are who we are, but we do mature over time. So there's kind of 3 layers:
1. Us (i.e. your soul, who you are)
2. The issues we deal with internally & physically (personal barriers, emotional problems, mental health issues, and physical restrictions)
3. The world (the situations we deal with)
We only see other people as other people, but really, people don't interface directly with the world, they interface with their current worldview & with their own hang-ups. Like, I have ADHD, and I didn't get diagnosed until my mid-20's. The short definition is "simple things are hard", which means that trivial tasks feel like Mount Everest sometimes, which means you get labeled as being lazy or just "needing to try harder", when you're really operating at 100% all the time just to keep up & are constantly exhausted & as a result distracted & prone to engaging in avoidance behavior.
Eventually, I recognized that ADHD was not a solvable problem, because the equipment to function like a neuro-typical person just wasn't there in my head, so I shifted to a management strategy rather than an elimination strategy. All that means is that I use checklists & reminders to manage my productivity, and suddenly my productivity shot up a thousand-fold because I was using an external digital notes & reminder system, rather than trying to keep it all in my head.
In addition, I had some health issues, including undiagnosed sleep apnea & an undiagnosed stomach issue that prevented me from eating regular stuff like gluten & dairy for a long time. I was pretty low-energy in grade school, got the food thing figured out for about ten years, and then got on some medicine so I could eat real food again, then got diagnosed with hereditary sleep apnea last year. And boy what a world of difference feeling good makes for what you can do with your life! It almost entirely eliminated my anxiety
So for me, I went from a pretty low-energy person with crap focus to a reasonably high-energy person who gets stuff done on a consistent basis, which for me were both pretty huge changes in my life. I have also matured in a lot of ways & become a lot more empathatic over time. Plus I've learned more about the kind of person I want to be, which pretty much boils down to two things:
1. Be kind
2. Do good work
It's so easy for me to fall into the trap of complaining & being negative, and to take the bait from trolls, and eventually I just hit a point where I thought, you know what, there's enough darkness in the world, I'd rather be a light & put out some positivity instead of being yet another person on the Internet flinging monkey poo. That, and there are enough con-men & rip-off artists that I wanted to contribute good work to the world, not shortcut work & not scummy, scammy work. Once I got that headset straightened out, it kind of cleared the way for how I wanted to live my life...I don't want to be a jerk, I don't want to be closed-minded, and I don't want to contribute more negativity to an already negative world.
I try to cut other people a lot of slack now too, not so much because they necessarily "deserve" it (that sounds bad written out LOL), as much as if I'm being really honest with myself, I need a lot of slack cut for me too, so fair's fair, you know? We all let ourselves slide & we can all stand to do better & if we live in an eye-for-an-eye kind of world, everyone's going to be blind haha. It's hard sometimes because I have to choose to get out of my own way from my default reactions to things & chill out a little more & try a little bit hard.
One of the biggest changes in my life has been adopting a strong personal productivity system (PPS), which is the way we get organized & get stuff done. I didn't realize this tool even existed before or that there were varying levels of qualities available to choose from, and simply by adopting a strong PPS, you can virtually improve your life overnight with very little effort! I don't feel like I have to try so hard all the time every day now because I have a tool that managements my commitments for me, so that I can focus on the execution rather than management of my responsibilities. That in turn has made me a more reliable person to myself & to others, which has translated into a lot more personal enrichment (better energy, better health, house is clean all the time, car is maintained, etc.) & more job opportunities, because I've gone from being reactive to being the go-to reliable guy who gets the job done & keeps people in the loop, which were things I had no idea how to actually do consistently in practice before!
So I think it's really more about maturing than changing, in most cases. Like, nothing's changed underneath...I still play Half-Life every Thanksgiving, I still enjoy neffing on ATOT & reddit, I still spend way too much time going down Youtube rabbit-holes, but on the outside surface, I can at least pretend to be a well-put-together adult these days, haha!