One of my favorite facts about Earth compared to the other rocky planets is that it's the only one that has a magnetic field. Mars is too small and has cooled down to a solid core, while Venus is theorized to not have a solid core at all. Mercury does have a molten outer core and a solid inner core (which is really fascinating though I don't have time to get into it now) but it rotates too slow and is too close to the Sun for it to be anything more than trace.
And while I can't draw I think that fact would be really fun to incorporate into an Earth design.
Imagine: Earth with the typical blue-and-green hair and patched skin, but his eyes are a molten amber. They flicker like fire in the Sun's light, and are subtly different every time you look at them. When he's hit by a solar flare, they turn into a combination of red, green, and purple.
