Drink the blue potion.

"Alright", you say, your mind made up. "I'll do it!"

Fred and George look at each other, grinning.

"Thanks, Harry", they say enthusiastically.

"But can we ask you not to tell mum?" George asks, his smile shrinking slightly. "You saw how she was back at the Burrow."

"Actually, can you not tell anyone else?" Fred adds. "I don't want Ron or Hermione to accidentally let something slip in front of our parents."

You nod assent, and pick up the blue vial. When you uncork it, blue vapour rises from the opening, making shapes in the air, before dissipating. You take a deep breath, then swallow the vial's contents with one gulp. The liquid burns as it goes down your throat, making you cough. The vial drops from your hand onto the table, and George catches it before it rolls off.

"Are you okay?" Fred asks anxiously.

The cough in your throat eases, and you look up at the twins, who are going at you intently.

"What does that liquid do?" you ask, somewhat belatedly.

"It's meant to turn your skin blue", Fred replies, "but all that's happened so far is that we burp blue bubbles. Fun, but not what we wanted."

You can feel the liquid in your stomach, slowly being absorbed by your body. Small tentacles of fire slip into your veins, and circulate throughout your body. You absent-mindedly scratch your arm.

"Tell us what you feel", George said eagerly.

"I can feel the liquid moving through me", you say. "Is my skin turning blue?"

"Not yet", George replies.

Suddenly, you feel light-headed.

"I'm feeling a tiny bit dizzy", you tell the twins, standing up as you do.

The twins stand up, and rush to stand next to you.

"Let us help you", Fred offers.