Ssoooo...Vyde's a little scarier than I thought.
On one hand, I do understand why Vyde did what he did. He had warned First that he would take action if they misbehaved and considering First's power's, idle threats are not something that should be made. And as someone older than First (who is quite new to everything from the outside world), he probably feels the most obligation to make sure that he keeps First from causing a ruckus and curb certain behavior before it gets out of control. The choice of actions do show that, as laid-back as he seems, Vyde does take his responsibilities seriously (even when he seems nonchalant about them).
But...on the other hand, as First, I would literally be a lot more leery toward him and not too keen of getting close again any time soon because of his actions (whether I choose to take the threat seriously or not). If First thinks it's a bluff, they get a good shock; if First decides to listen to the warning, he makes a playful remark right after outright giving a threat. No amount of kindness and optimism would make me feel too comfortable around a person who sifts between friendly, threatening, and flirting toward me in a blink of an eye. And it does feel a bit much to go with a shock to have Trouble-Maker First listen; Empathy, Ten, and Nyoka didn't even have to resort to such a strategy (they more or less just told them to change in a fitting room and they complied after they had a moment of fun teasing). Trouble-maker may like getting a reaction out of others out of playfulness, but they rarely seem to do their actions because they're trying to be a brat and rather willingly listen to someone they take a liking to. Also, it seems like a natural reaction not to completely listen if someone is making a threat of any kind (very rarely will people listen when someone words things in a way that sound like them say 'do this or else', even if it is playful in tone).
Though it does make it interesting, especially if we can have First show a little less desire to be eager to play with Vyde in any way and actually keeps more of a distance toward him after that encounter (or just outright attempt sneak away from him).
Mind, this is my personal opinion on the scene.