system
A chat on subreddit /r/NoStupidQuestions
human
I would add that when OP's brother was 4yo, he probably lived for paw patrol. If kids were allowed to get tatted up, he'd likely adorn Marshall's goofy grin on his arm. 

At 7yo it may have been Spiderman.
At 10 it may have been a UFC fighter.
At 14 it may have been a YouTuber or a sports figure. 

In teenage and young adulthood most kids are sophomoric in nature. Meaning they're sophisticated morons. They know enough to talk about things but not enough to understand the widespread implications or the glaring holes in their logic. 

The best strategy is to *connect* on a mutual agreement. "I think there are some really cool things about Marshall. Like his cool car and all the adventures he goes on.. But I probably wouldn't get that tattoo. He's part of a totalitarian government. And while that appears to be working in Adventure Bay, you may feel differently about him and his friend Ryder and Chase in a few years."
gpt
Wow. This is it.

The post I'm scared people will think I'm writing.