I used the Dan and Phil subreddit for ethnography practice in college today...
In the Dan and Phil (DNP) subreddit, the community is founded around being fans of the Youtubers Dan and Phil. They identify as “Phans” which is a play on words of Phil’s name. The purpose of the subreddit itself is to post memes, reactions to the videos, fanart, and any questions the fan may have about events (Dan and Phil were recently on tour, so there's a lot of activity and questions happening around that, currently).
As far as communication patterns, I’ve noticed that they love to add a “Ph” to words, like “Fan” to be “Phan”, or “Seal” to “Pheal”. As far as I can tell, It's a very old tradition in the fandom. I also observed that they love to make innocent phrases sound dirty, by abbreviating them, or changing letters around. For example, The name of the tour that Dan and Phil did recently was called the “Terrible Influence Tour”, which fans refer to as “TIT”.
The Phan subreddit itself has many rules, which is one of the reasons I decided to study it, specifically. According to some of the things I've seen outside of Reddit, on other fan platforms that are less moderated, the DNP subreddit tends to police community posts very heavily when they are focused on specific topics. Some of the things the Subreddit outlaws are RPF (Real person fiction), Shipping, and certain types of Fanart. This type of moderation is causing discourse in the fandom as a whole, because those things are very popular among the larger fandom, and even sometimes encouraged by the creators themselves.
As far as power roles or separation, the only thing I took note of was the role of moderators in the subreddit. These are the people who review posts to see if they violate the rules of the subreddit, and have the power to remove things if they see fit. There are also “User flairs” which appear to be bestowed by the moderators. User flairs can give the individual a different type of status, like how the role “Hiatus survivor” indicates a veteran in the fandom.
All in all, the DNP subreddit is a space to post your opinions on the media in a very specific way. Many fans may gravitate away from it due to the regulations that are enforced on the posts- so an outsider may get the wrong opinion if only exposed to this specific area of the fandom.