As he was a so much more powerful mage than Marci, as telemancer, Therius could easily know that Marci was hiding nearby when Emma was attacked by the thugs and he really didn't appreciate what the girl did.
That was why he looked at Marci with a murderous glare. Marci didn't know Therius was a telemancer who could read her mind and knew what she did earlier. Therefore, she felt attacked by the man's obvious dislike toward her.
"Hey, Marci," Emma didn't know what happened and greeted Marci well. Inwardly she felt relieved that she didn't use any other powers than herbomancy. Who would have thought someone from the academy would really see her in the night market?
If she tried to chase Xion with aeromancy earlier, there would be a good chance that Marci would see her and know that Emma was lying about her abilities. She was not just a herbomancer, but also an aeromancer.