Tonks | Cassiopeia
I imagine that to be told you could do anything must create a tremendous degree of pressure and uncertainty. But they were certainly right that you're magically talented! And control comes with time. I used to always ask Pollux for help. My brother. He was in the fourth year when I started.
Do you know, I agree with you entirely on the matter of 'dark magic'. It's a very unhelpful classification. There are all manner of everyday spells that could be used to harm someone. The Ministry usually gives something the 'dark magic' label if they want to prevent people from learning about.
Now, if you ever need help with runes, ancient languages or Arithmancy, I'd be much more useful.