Murderbot communities (Tumblr, FB, Reddit)
When you have just finished reading (listening to) the Murderbot Diaries and are dying to share your thoughts with other fans, you will probably look for some communities. There are multiple communities on multiple platforms.
Tumblr
As of now, there are five Tumblr communities that can be searched with the keyword "Murderbot". The two larger communities "The Murderbot Diaries" (1K+ members) and "Murderbot Diaries - Book Only" (200+ members) have probably been around a little longer than others. The Book-Only community, as the name indicates only allow posting things based on the book series, whereas "The Murderbot Diaries" has lots of post based on the TV show, too.
Many people simply post and interact outside of the Tumblr communities, that is, they just post to their own blog. You can search posts with tags, such as "#book title", "#murderbot", "murderbot diaries", and "#tmbd".
You can also use portmanteau ship name for looking for blogs, art, etc for a specific combination of characters you like. But there are multiple portmanteau and their interpretations that exist and quite often it can open a can of worms if you are not careful. You might use one while meaning something a little different and end up getting blocked by some people. Getting blocked can hurt, but it is a way for lots of people of curating their experience and usually not personal. My observation is that portmanteau is used for (mostly) romantic relationships, and not platonic ones whether they are QPR or not. (I say 'mostly' as some people use portmanteau name for non-romantic, which makes it confusing.)
There are several Murderbot/Martha Wells related fangroups on Facebook, both private and public. I only had had a glimpse, so I cannot give much information. But from what I gathered, people post things using their regular account with their real name visible. Perhaps not for those who want to keep their fandom activity anonymous.
There are both one for the book series (https://www.reddit.com/r/murderbot/) and TV show (https://www.reddit.com/r/MurderbotOnAppleTV/).
The book subreddit seems a relatively small, low-drama community focused on sharing thoughts on the books, characters, the authors, and event reports.
The TV show subreddit was created for fans from the tv show who are not familiar with/interested in the book series, but also to keep the original subreddit free of too much tv-show discussion.
The tone is generally mild in both.
I will make another post on Discord servers.