'Thank yooooou' (spoilers)

I'm sure this has been covered before, but I haven't seen the topic discussed recently, so I'll just ask...

After the double-date and Parry is being "attacked" by the Red Knight, he runs into those two hoodlums and just before they beat him into a coma, the Red Knight draws his sword and it parallels with the one hood pulling out his switchblade and then cutting him with it--though through Parry's perspective it was the Knight that drew blood.

From what I've gathered, the Red Knight represents Parry's destroyed, tainted former life as Henry Sagan and probably the reason he wanted to become Parry, just so he could distance himself away from a life of mourning, pain and suffering. I'm at a loss with how or why the Knight parallels with the two punks for? What have they to do with the Knight other than the fact that they're enemies of his?

And that leads me to my next question, why does he thank the Knight after he slices him!? Is he thanking him because he believes he's finally putting an end to his madness? His life as Parry? I'm not so sure I understand.