Vampire Diaries season finale. Shouldn't Damon know that it was Katherine that he was kissing to?

Yes! But the look on his face after! He looked very confused, and kinda shocked. Maybe that couldn've been from "Elena" kissing him, but maybe he did realize it. Especially after he kissed her. He knows Elena wouldn't do that to Stefan. So I think he probably knows. But i don't know! Can't wait till season two!!! :D

Maybe he knew but didn't want to say/do anything to Katherine that would let her know that he knows? He looked a bit strange after Katherine went into the house, like he was trying to figure something out.

when Jenna INVITED!!! her in Damon wasn't sure but if you can see he touched his lips as if saying "i taste this before could it be Katherine??" and he was like u would say CAUGHT in the moment OMG!!! i just realized something Katherine is invited in ans what would Elena react when she sees KATHERINE PIERCE!!! and what would her aunt do?? will Katherine be jealous of Elena cuz the two brothers r IN love with her!!!

i would think so. I mean to me that be a dead give away-no pun intended- but i mean i may be imagining this but i think he kind of knew it was not Elena after the kiss, when he touched his lips it was more of a "hmmm" moment not a "Yay she kissed me" But yes he really should have known better. After all Katherine was the love of his human life and most of his vampire one. Wonder what will happen now?....

so so so true!!!! i was in shock when i saw damon kiss her!! but more angry that "elena" let him....but thankfully we all know it wasnt elena but it was katherine.. maybe damon might think about it? uugghh def. a great finale!!!! loved every moment of it!!!!!!

Aw, I thought it was Elena at first, so thought it was so sweet! I think he raelized something was wrong afterwords, but wish it was Damon and Elena! The kiss was so sweet, but after she killed Elena's dad and Elena was coming back home and couldn't find her outfit. But Damon and Elena would be so cute together!!!!

after the aunt shut the door on him. if you look at his face he touches his lips and knows somethings different. im pretty sure he knew that it was katherine. i was so happy when he and her kissed and now i find out its not even elena:( or elana? haha but i love damon<3333 i was so sad when anna died:(

THATS WHAT IM SAYIN, I MEAN SHOULDNT HE HAVE SENSED HER IN THE BEGINNING? AND DAMON'S ALL SWEET AND CONSIDERATE, EW.

well since he has super sharp hearing mabe with all the talking he didnt notice there wasnt a heartbeat. its not like he does a daily inspection of it. and when he was kissing her for the FIRST time he wouldnt have even noticed. and i dont get why people are saying that he looked like he was trying to figure something out. no duh hes going to be shocked! he knows she loves his brother and she also had the lets be friends talk with him.