Damon was gonna kill Caroline and he was about to stab her with a broken wooden chair stool and as he was about to, you jumped in the way and Damon stabbed you instead and before you fell to the ground you looked at Caroline then fell to the ground and Stefan quickly ran over to you and he could hear you weren’t breathing and he knew he didn’t have a choice… he was gonna turn you into a vampire, he couldn’t stand life without you, he knew it was wrong but it was for the best and he bit his arm and put it in your mouth so the blood would go down your system but he didn’t know if it was to late to put the blood in or not… which made him even more worried

(Obviously you were human before he put vampire blood into you’re system)