Velly

 Velly is incredibly sweet and incredibly shy. Especially around strangers. And sometimes friends too. Most people she meets are not aware that she can't physically talk, but honestly, even if she still could, she probably wouldn't do it often.

 She can often be a little impulsive, often forgetting to look both ways before crossing the street, but she does her best. She's also very incredibly bad at driving, and was never able to obtain her full driver's license. Luckily, she has a good friend to drive her around when she needs it (since she's also too nervous to take the bus)!!

 She is very very good friends with Nick!! Velly loves him a lot, and is very protective of him (though it's not like there's a lot to protect him from), and is very supportive of his musical talent. He's probably the only person she truly feels comfortable joking around with, and boy, does she joke a lot. Unfortunately for Nick, Velly is very very fond of bad jokes and memes written in a text-to-speech program on her phone. 

Velly lost her voice after an unfortunate car accident when she was 16, and she suffered a bit of brain damage after the incident. Luckily, though, she was able to recover mostly.