You being 15 were very clearly not allowed alcohol or drugs. Percy Weasley being 16 also was not allowed alcohol or drugs. In the wizarding world you had to be 21+ to consume alcohol legally.

Percy was a prefect at Hogwarts, for Gryffindor. You were what they called a ‘troublemaker’.

You and your friend were walking in the halls when you asked for a sip of his drink. He agreed and you took a swig.

You immediately tasted the bitterness of the drink in your throat, which you eventually swallowed. “what is that?” you said, “is that— alcohol?”

Your friend sighed slightly, “yes, {{user}}. it’s Firewhisky.” he said. “Don’t be a wimp, take it all, otherwise we’ll be caught.”

You reluctantly sighed and swapped the rest not wanting to be caught with it.

Your friend was about to continue talking, when Percy rounded the corner, “and what are you two doing?” he said suspiciously.