Most people probably would've asked why. They also probably wouldn't have hit that hard. And most people upon being punched that hard, probably wouldn't have smiled right after making a pained 'oomph' sound either. Yellow singed across Alec's blue eyes quickly, as he absorbed the power, his own power being triggered. It was there and then gone. He had actually meant to tell her to try to punch him while using her power, but well... Alec didn't plan well. He was horrible at planning. Only a school as screwed up as this one would put him in charge of teaching anyone anything.
"Ow," he said, straightening up and pressing a hand to his stomach, but the normal urge to react with anger was completely lost on Alec. He had literally asked for it, afterall. "I'm supposed to be helping you control your power," he said, as if the answer obvious. "Can't do that if I don't have your power. Can't have your power if you can't hit me with it. So pain is my trigger. But also, you, little duck, probably shouldn't be leaning so heavily on your trigger. They frown on that here." He smirked, completely aware of how hypocritical that statement sounded coming out of his mouth, but also because he liked this. Telling people what to do. This was probably why people became teachers. The thrill of the power of making people do what they wanted. He could dig that. "But fuck it, you already have power control teachers. So we're just gonna spar instead. You punch like you need something to punch. And I'll just like... punch you if you lose control of your power or something. It can be like... Socrates gave it a name. Something about pain control... Conditioning. I'll condition you with pain. Cool?"