Is Amortentia illegal?

Potion informatio. Love potions were considered to be powerful and highly dangerous. Amortentia was the most powerful love potion in existence. Love potions were banned items at Hogwarts School of Witchcraft and Wizardry, though students still smuggled them into the school through various means.

Read more

And another question, why is the girl obsessed with ron weasley?

In 1996, during her sixth year, Lavender developed a crush on fellow Gryffindor Ron Weasley. She took to complimenting him and flirting with him, which Ron seemed surprised and flattered by, though he was interested in Hermione Granger at the time. Who is the girl that likes Ron? Lavender Brown Lavender Brown is Ron Weasley's love interest in "The Half-Blood Prince." Warner Bros. Cave featured most prominently as Lavender in "The Half-Blood Prince," where her character becomes infatuated with Rupert Grint's Ron Weasley and engages in a very pubic, PDA-filled relationship.