This is just my personal interpretation, but since Silver has a strong sense of justice, I think that while he might have a somewhat gentle expression toward the person closest to him, when heโs in battle, heโd be highly focused on analyzing his opponent and identifying --
their weaknesses. Also, the fact that he uses psychokinesis seems to further prove his high level of concentration. Thatโs why, when Iโm drawing him in a focused state, I tend to make the crease between his eyebrows a bit deeper... ๐ฅน