Sif raised an eyebrow -- no, actually, Sif raised both of them. "How would you have been?" she asked, entirely lost. Her expression was a little bit arena judge and a little bit paranoid horse owner, but mostly she just seemed confused by the question.
There was a mounting block, but Katie wasn't very tall and a swift mount certainly didn't bother her -- even if she was kind enough to start walking while Loki was trying to settle.
"Hey! Katie. No." Sif disapproved, but not of Loki.