Andi was a late talker, something which concerned her parents quite a bit, especially Glimmer. Despite the assurances of the healers that she was healthy and there was nothing physically effecting her ability to speak (her hearing was fine and she could vocalize in a way that indicated she was capable speaking if she needed/wanted to), their concerns only grew as more time passed and she didn’t say anything.
She didn’t actually start talking until she was about two and a half years old…And her first words surprised Glimmer quite a bit, not only because by that point there were serious concerns over whether she’d speak at all, but also because the first time she spoke, it was in a sentence. A simple one - “I don’ wanna” - but that certain gave Glimmer a shock when she heard it. Her parents were, of course, overjoyed to hear her start speaking, and her vocabulary grew quickly.
The timing of Andi starting to talk may or may not have been related to the fact that Luna had been born not long before then, meaning that Andi was now dealing with the fact that she didn’t have the undivided attention of everyone in Bright Moon. Some people theorize she started to talk to get more attention from the adults.