Oh.My.God. I just realized one thing!
Do you remember when in 1x22 Damon tells Elena/Katherine that Bonnie was a good person because she had saved his life? He said “she helped Stefan save me”. Do you remember that then he said that she had obviously done it for Elena? Do you remember that he said to Katlena “Somewhere along the way you decided that I was worth saving”?
And what did he say in 6x08? “When the opportunity presented for me to comeback, she made sure I took it” but this time he knew she didn’t do it for Elena. He knew that this time it was Bonnie that somewhere along the way though he was worth saving.