TooManyAnnas had an interesting post a few days ago about whether your characters actually know each other ICly. I started to make a reply to it... and realized that my reply would be almost as long as the post itself. So, figured I would make a post here. XD
Firstly, I have a lot of characters, even if you only count the ones on Feathermoon. So bear with me. Starting with my "mains" and going down the list to my liddle baby alts...
Alanon, Pitch and Quae are all siblings, along with 2 of my sister's toons, so of course they all know each other very well. Lark is Pitch's mate/partner, so she also knows his family through him. Barraccus is Quae's partner and is equally familiar with the others. And Shaurria is Alanon's adopted daughter and Pitch's protege, of a sort, so she's quite familiar with them too.
Rheugan came to know Pitch first, then Alanon and Shaurria both. Pitch and later Alanon are his mentors (though Alanon might also be considered his healer), and Shaur is his best friend. Later he met Arvoss, who is Shaur's "other father," and Arvoss came to be sort of a fatherly figure for Rheu, too.
Rillian is an old, old friend of Lark's, and when she took up with Pitch it was inevitable that he and Rill would meet... although they don't like each other much at all, so they try to spend a minimum of time in each other's company. Roebar is the "new kid," who happened to know Rheugan, at least in passing. He's since met Lark as well, and I imagine he's probably run into Pitch at the Pig at some point, but he doesn't really know anyone "well" yet.
And now we start getting into my less well-known characters....
Arnen has met Lark once, when he came to the Pig looking for his lost brother (sis's character), but that was it. He hasn't met anyone else unless it was simply passing them on the street. Turron and Rhiany are my father/daughter pair, so they know each other. They have also met Lark, back when she still worked for Stormwind University (she got saddled with interviewing Rhiany for acceptance into the school). Rhiany took a liking to Lark and they'd become sort-of-friends before Lark left the school for the Riders. Neither of them know any of the rest of my characters.
Davoss is more complicated. He is Arvoss' son, so they do know each other... but Dav believes his father was killed in Stratholme, and never found out he was raised as a death knight. Arvoss has been keeping tabs on him from a distance, but considers it better to leave things this way. Dav has met Pitch, who invited him to the Pig one night, but other than that he doesn't know anyone else. I keep meaning to have him discover Arvoss is alive (sort of) and have a reunion with the 2 of them, but so far no good opportunities have come up. Oh well.
All my Horde toons know each other passingly well. Kaledain and Khaotic are married with a daughter, while Taurros is a casual friend. Booggah and Rajast are more like acquaintances that they can call on for help/favors every now and then, though I wouldn't exactly call them friends.
And Taurros has also met Rheugan. XD
That's all for Feathermoon. My characters on other servers are scattered, but I do have a few more that have relationships of one kind or another...
Andrano and Carienne on Silver Hand are traveling companions (and likely going to be more, if I can ever do some more writing for them).
Khlar and Gwynifar on Wyrmrest Accord are brother and sister.
The rest are mostly just random alts I play when I need a change of pace/scenery/whatever. While I do play them in-character (in my head, anyway), they're not what I would consider "real" characters, so I suppose that concludes my list. Whew.
I did tell you I had a lot of characters...