We adopted a cat when it's owner passed away. She was a very pudgy cat and her name was Li'l Girl. The cat we already had is petite and twice the age of the new cat. She also was born without much of a tail, a little puff is all she has. Older cat's name is Jazzy but I usually call her my baby or jazzer. The younger and newer cat has a normal tail and is much larger than Jazzy. I could not make myself call her Lil' Girl, since she is so much the larger cat, so we started calling her Tail Kitty or Tail Cat.
A diet brought back her slim gracefulness, but she is still much the larger cat, so TC, or Tail Cat seems to have stuck. She was 5 when her original owner passed, but she has made a great adjustment and is happy here.