I have developed a theory that Lila may have followed Adrien before the timeline we see within the series. Adrien is famous worldwide; while some people have no idea who he is (like the main character of the series didn't know he existed until he was in her class), overall, he can not go anywhere without being recognized by someone. When we first meet Lila in the series, she’s talking to Adrien. When I realized that Lila’s character wouldn’t exist if it were not for Adrien, I started to take note of all the odd things Lila did in relation to him.