Nika, wait Helena? No... Nika in Helena's body walked out to the whomping willow with her "Slytherin" robes on. She found a nice charm to change the red to green so that she'd appear like a more "believable" Helena. The only problem was that she didn't know a thing about the girl. The had only just met in that very potions class that they made the polyjuice.

So how is Nika supposed to walk around the school pretending she's Helena if she doesn't know anything about her?! Hopefully none of Helena's friends, whoever they may be, try to talk to her. She wouldn't want to ruin the girl's life.

Now to be Helena-ish? She continued walked around keeping her head down incase so that incase if someone tried to come up to her they wouldn't have a chance of starting a conversation. Being Nika was a lot easier than trying to be Helena.