Now that I've finished playing Skyrim for 13 hours...
...I can say that I'm up for backthreading with all of my characters! It may be waaay difficult for some, and not so much for others.
Kartahn is one of those that it'll be hard for. Unless you go to school with him and have spoken to him before, he won't have much to do with character relations. So if you want to relate with him, that's fine by me!
Slade... lol, no. Slade wouldn't give anyone the time of day. The most you can do for Slade is just have had some kind of encounter with him during the past that can be played out. He doesn't allow friends in his life.
Lyon is one of the easiest to have CR for. Because of his unique position, he will definitely have had many encounters and it is really simple for him to have encountered a character in the past, especially if they're upper class. I'm completely willing to make any kind of encounter happen with him, because I'd like to flesh him out more.
Levander is... debatable. Unless your character came to Isgar Manor or Levander ran into your character at school or on the way home from school, she won't have much for CR. But I'm open to her, of course.
Rene is almost as easy as Lyon. She's out frequently, so she's met a lot of people.
Remy is someone who NEEDS CR. Anyone who wants to have a prior encounter with Remy is more than welcome to~. Just let me know!
Yggdrasil... will not have CR. He never leaves. Unless someone visited Black Manor in the past, he'll be CR-less.
Florence is very likely to have CR just because of how varied his locations are. He's also someone I encourage people to relation with because I'd also like to flesh him out more, like Lyon.
Rudalotte... lolno. No, but seriously, I guess she could. XD Only if you're upper class, though.
Last but not least, Dominic. Dominic's that guy that knows everyone and if he doesn't know you, he will eventually. There's probably a whole slew of encounters for Dominic, and I'm open to all of them.