Up till recently between the twins, Thing 2 has been Daddy's girl. And what I mean by that is she is the one who always wants to be with Daddy, will occaisionally only be consoled by Daddy, and sometimes refuse to go to Mommy when she is with Daddy.
Recently, Thing 1 has started the same trend. She will frequently get very upset with Mommy and refuse to go near her or interact at all. She then of course runs to Daddy. In addition, when she wakes up in the morning or at random times during the day she will call out "Daddy, are you?" This has become a running joke that when she wants attention of any sort or needs something she calls for Daddy. Thing 2 has not learned this tactic yet.