Knowing a lecturer from a previous course of study, would it have an impact? I am a final year honours student (UK) who has come across a little bit of a predicament. About eight years ago when I was a teenager, I was undertaking a University course that I did not complete because of personal related issues. There was a lecturer that I did not get on very well with at the time because of this who I knew both from that and also from my previous school days. We had an argument once or twice; I was fairly young at the time. 

When I started this new course a few years ago, (which is at a different University) I committed to achieving as much as possible, and I have managed to get a 'first' overall in terms of averages for years one and two. However in my final year it turns out that one of the examiners for my final year project is the same lecturer that I described above in the first paragraph (even though it is a different establishment). 

So the question really is, should I have a reason to worry? Would under-performance as a teenager result in an unsettling experience or a bias of marks when it comes to the day when the viva is to be presented? My friends tell me that my worries are irrational as eight years is a long time and teenagers often under perform, but when I started to see if anyone else had this problem, I could not find any existing questions, and everyone on this community looked to be helpful in providing advice. If you could share any enlightening thoughts, it would be very much appreciated!
Anybody who has taught and likes teaching knows that one of the biggest rewards is seeing your students grow.  From your description, it sounds like your only problems in your previous encounter were age-typical lack of focus and brattiness. If you are now a much more mature and polished student, then more likely than not, if the lecturer remembers you at all, it will be to your advantage when they compare with the kid they taught so many years ago.