Alphys is a nerdy, shy recluse with a fondness for human anime and manga. She is very insecure, worrying about what other monsters think of her. Her failed experiments with Determination that involved the creation of the amalgates contributed to this, as she was filled with guilt, told nobody, and became depressed. She has a crush on multiple characters (some mild, others more serious), but struggles to communicate her feelings

She can get real gassy to her own embarassment.