Myungsoo is being cute and Sungjong hates it. Firstly, he hates it because being cute is Sungjong’s thing and all his hyungs know that. Secondly, he hates it because Myungsoo is only supposed to be cute behind the scenes, when the members of Infinite are the only ones who can see just how adorable Myungsoo really is (Sungjong wishes that rather than to all the members of Infinite, Myungsoo would only be cute to him, but he knows when to stop hoping).

Sunjong also hates when Myungsoo smiles in that way that only Myungsoo can (dorkily, Sunjong thinks) and the fans lose it. And he hates how he loses it as well when that same smile is directed towards him, and only him.

He wants to say all of this to Myungsoo, but he doesn’t. He thinks he probably won’t ever say any of this to Myungsoo. Sungyeol notices that Sungjong sometimes hits his bear longer than usual and mumbles at it to “wipe that cheeky smile off your face.” (Choding Sungyeol smiles more after he hears this. Sungjong doesn’t react.)

This is normal to Infinite. Normal for Sungjong to vent his anger onto a stuffed bear, rather than to confront his hyungs. It is also normal to (most of) them when Sungjong starts to ignore a certain member of the group. Sungjong wouldn’t be Sungjong if he didn’t do weird things like this, would he? Five out of six of his hyungs are not concerned.

Five out of six of his hyungs brush it off.