She will have Stefan's and Damon's blood on her system and she'll die...

I actually think it would be kind of cool if Katherine turned her. Think about it: it would be quite unexpected. Plus, she could give her the blood and kill her, and only Elena would know and then Damon, and Stefan too, would be upset over Katherine killing her, but she would do it to give a clean break between her and the brothers. Then Elena will be a vampire and Damon will teach her the ropes. I see a fanfiction story coming on...

Katherine would probably do it to hurt Stefan. I don't actually think Damon would turn her, because he wouldn't want to see her go through something like that. I don't think he'd want to cause her that pain.

damon cause stefan would never do that if she asked him...but damon would.