Silver is a female sloth that Queen Glory found (or Silver found her) and eventually decided to keep as a pet in the third book of the Wings of Fire series, The Hidden Kingdom.
Glory found Silver when she woke up from her first suntime (nap during the day) with a sloth on her neck. Glory initially tried to get the sloth to climb off, and was stopped by Jambu, who explained that the sloths were the pets of several RainWings and that Glory had been "chosen" relatively fast. Upon visiting the other dragonets, Tsunami tried to eat her (earning some disapproving looks from RainWings nearby) while Sunny believed she was cute. Silver's presence caused a fight between Glory and Tsunami when Glory got defensive about Tsunami wanting to eat her sloth. Starflight was astounded that the sloths weren't afraid of the dragons and was itching to take some notes.
When they find the half-dead, decaying sloth by the tunnel, Glory blocked the gruesome sight from Silver with her wing.
Later, when Glory was exploring the tunnel leading to the Kingdom of Sand, she told the other dragonets that she had named the sloth Silver and gave her to Sunny to keep safe.
At the RainWing Royal Challenge Queen Magnificent startled Silver. Silver, afraid, runs toward Glory and reveals her hiding spot.
Silver expresses her feelings for suntime clearly even though she can't speak. She loves Glory and is very attached to her, as shown when Glory returns from the Night Kingdom; Silver explodes from the tree and clings to Glory to "chastise" her. Also, when Queen Magnificent scares her, she ran right to Glory. Even though no dragon should have known where she was, Silver still found Glory. She also seems to enjoy spending time with Sunny because of her scales that radiate heat. She knows Glory is pretty disagreeable, but likes her anyway.