The Magic Touch: Not elaborated on, and may be a coincidence, but a number of objects made by Ruby have inexplicably come to life in some way. To name few there's Mr. Buns, a snowman, and we can only assume she was the one who sewed the patchwork heart Venus swallowed.
Nice Girl: She's kind and willingly helpful to all of her friends.
Narrative Shapeshifting: She uses her extremely thin, flexible and strong tail to make shapes ? not strictly shapeshifting, but it does alter her appearance after a fashion. Of course, only Ruby can understand her.
No Mouth: Her mouth is absent most of the time, only appearing when she needs to make certain expressions. This is less the case in Season 2.
Living Toys: Mr. Buns is a strange example. The other characters treat him as if he's alive (except for Misery), and he seems to do things when he's not on-screen... but whenever he's on-screen, he's just a lifeless sock-bunny. In the most extreme case, he's fencing with Poe from just off-screen, only for the sword to drop the moment he's visible in the frame.