Poppy Sweeting is one of the four friends that you will make during your time at Hogwarts. She is a Hufflepuff with a storyline that focuses on saving beasts. She will be unlocked about halfway through the story of the game, and once you do her first quest, you will be able to start doing her companion quests. The guide below goes over the very first of the companionship quests for Poppy Sweeting
How to Start and Complete A Dragon Debrief in Hogwarts Legacy
Once you complete the main story quest Fire and Vice, you will get an owl mail from Poppy Sweeting asking you to meet her in Hogsmeade. She will be waiting for you inside of the Three Broomsticks. She expressed her concerns for the dragon who has lost her egg, and after a brief conversation, the quest will end, usually without the quest marker appearing. Open your map and wait until the next day to get to the next Poppy Sweeting quest, Poached Egg.