I once had a 20 min long duel with a hacker in Dark Anor Londo once. It was so intense and while we were having our duel he popped some divine blessing. Most annoying was that he could take 3 15+ Richards rapier with hornet ring backstabs. I managed to get 4 hits on him when I ran up to the princess' chamber. And sadly, after that long duel, I only got 13k souls ...
But if you want to have a lot of PvP, kill Gwynevere to get invaded, then stand in the big chamber around 21 - 00:00 O'clock and people will invade you like that. I once got invaded by 2 Darkmoon and 1 dickwraith at the same time playing there. Later on I was invaded by 9 Darkmoons in a row, so intense and fun
Also lost 2 mill souls in Township due to some cunt hacker