Maybe they were both different, but one thing that would never change was that Rose would do anything for Lissa. That included giving her a little blood when she needed it. It wasn't like Rose loved the idea of being a feeder or the idea of what people would say if they knew, but Lissa needed this and Rose knew it wouldn't hurt her.
"Don't look at me like that, Lissa. I'm fine. No big deal." Truthfully, she was feeling a little lightheaded, but Rose wasn't going to let that show. She knew Lissa felt guilty enough and she also knew that wooziness from the blood loss would pass soon enough. Lissa hadn't taken much at all and it really wasn't a big deal.
When Lissa did tell her what happened, Rose swore quietly, but creatively. She knew her friend couldn't help it, she knew she couldn't have just left the girl there to die, but Rose hated what spirit did to Lissa. She hated it more knowing there was nothing she could even do to help her anymore.