Closet Snuggler

I've wondered why my cats don't snuggle with each other.  I know after introducing a new cat to a household that sometimes the other cat or the top cat doesn't want you to know that s/he likes the new cat.  Why is that?  I found out a long time ago that Midnight was a closet snuggler.  I came home to see this:

I can understand why Midnight wouldn't welcome snuggling with her sister Emily.  Emily was definitely hyperactive as a kitten and tended to jump on Midnight when she was sound asleep.  Fortunately Molly didn't have those tendencies.  She paid attention to cat body language and respected the other cat.  However, she's made several overtures to snuggling that Midnight has ignored.  The other day I turned around and saw this on the ottoman:

Midnight definitely looks relaxed and happy with the situation.  Notice that her tail and body are over Emily's, so Emily was on the ottoman and Midnight came up and laid down beside her.  Hmm.  Let's see what happens when the cold weather comes.