My wife pointed this out. In the dedication of Lord of the Rings Tolkien said it's not good to delve too deep into dark things.
Then Lewis dedicated the screwtape letters simply to him 😂
In Lewis’s That Hedeous Strength, Merlin talks about the fall of Numinor and the true west. I think Tolkien hadn’t published LOTR yet. Been hearing about cool connections between the two recently. Haven’t read any of these books in years. I mean to revisit them at some point now that I’m older.
The best thing I ever saw on Twitter, many years ago, was a "live-tweeted" pubcrawl with the Inklings. Inside references, someone who clearly knew the characters (and their writings) well... "Jack's flirting with the waitress again," ... it was clever and glorious. I doubt it will ever be topped.