Checking out some strong subreddit relationships stemming from a chosen root subreddit. The relationships below are ordered by User Overlap Scores from subredditstats.com. An interesting way of discovering related subreddits based on user overlap.

AgainstHateSubreddits

ConsumeProduct

Interesting dichotomy of users between AgainstHateSubreddits and ConsumeProduct.

ProtectAndServe

JoeRogan top 5 of 3

Sino top 5 and 3

Coronavirus top 5 and 3

These glimpses use the User Overlap scores from https://subredditstats.com/subreddit-user-overlaps. Look up a subreddit yourself, for fun.