In contrast to other shippers' opinion,Damon's Thank You after Elena kissed him wasn't only meant for the kiss itself she gave him,but in my opinion,her trust in him.Thanks for telling that she likes(and loves)him the way he is,that he doesn't have to change for anyone.That he knows there's a person who likes him because of his true character and isn't obsessive trying to change him,but nevertheless DOES. Thanks for her understanding for his behavior,his feelings and most of all for revealing his humanity.Instead of giving up on him,Elena always tried to break the shell,the stone wall which covered his heart.She was the only one who ever reached the core-and discovered his vulnerability,the part of unapproachable-seeming,devilish Damon that nobody else saw.The ''devil''of whom was told not having any kind of humanity left inside,no good,no true feelings.The one who has always been misunderstood without the others recognizing it. 145(or rather 500 years in the books) of not being accepted.Didn't people ever wonder why he exactly behaves this way?Wasn't there a slightest hint?Aren't people able to look behind the facades,to understand the unspoken language anymore?There were people who tried,but simply failed,maybe because of impatience,or maybe because they just didn't see that he doesn't need to hear that he's wrong or that there just still HAS to be a part that feels,but love,trust and understanding.Elena understood: In spite of rejection after trying to make him aware of his humanity(''There you go.Pretending to turn it off,pretending not to feel.''-''I feel Elena,okay?And it SUCKS.What sucks even more is that it was supposed to be me.Jules was coming after me.'')and following arguments , she didn't just let him go,not seeing any hope,BUT showed him that there's this one person who trusts him,understands the little signs his inner child gives,without judging him,but speaking the unspoken language,the only one to ever reach the child and human inside. Sometimes it's not words a person needs,but little gestures like looks,hugs or just the company which makes clear: I'm with you.And I'm waiting for you to show me what's inside-just take the time.There's no hurry.You don't have to behave differently,just be yourself.I'll always be by your side to remind you of the fact that you're not alone,not misunderstood,that it's not wrong to show feelings-even if you need a lot of time.
And through this long journey,the bond grew stronger and even Elena had to admit that she has strong feelings for him,that she actually loves him-because at the end of the day,it always comes down to the love of a woman.And she has to admit herself: If you love two people at the same time, choose the second one, because if you really loved the first one you wouldn’t have fallen for the second.

So that's my opinion on his Thank You as well as Elena's ''You're welcome''.What do you guys think?I'd really like to know ;)