I've noticed that Radium is circle themed and Radon is square themed including their tabby markings. Good job on the character designing, it fits them very well. I love how they are two totally different personalities. While Radium comes off as a very intellectual, confident, but a bit insensitive sort of character Radium seems like a bouncy, imaginative, and very sensitive. My favorite thing about storytelling is characters and their development which is probably why this comic entertains me so much, I'm also very obsessed with the Myers-Briggs personality stuff.