If I play as Metal in some roleplays, I'll have him as someone who's often stressed but doesn't show it. He often drums his fingers on a surface, bend some metal, or if he's left alone he'll tug at his ears. He often hides these habits from others, especially Cyber since he looks up to him.

Example.
In My Sonic Roleplay! By me, Shard walked in on Metal tugging at his ears, he's currently trying to help his brother break the habit.