mako and bolin parallel each other because:

mako kept everything soft and sweet inside of him, curled into a tight little ball while he trapped himself in a hard casing in order to protect his brother.

bolin kept everything hard and angry and destructive into a pit of lava in his soul, hoping it would never come out. he encased it in layers of softness and naivety because someone has to make sure that people doesn't consume themselves with their own anger but bolin being able to bend lava when there were no other "softer" options, while the fire burned in his eyes and you could see the stone and flames consume him and he knew that theres no other way to do this except embrace this side of you BECAUSE HOW ELSE ARE YOU GOING TO SAVE YOUR BROTHER WHO DID EVERYTHING TO PROTECT YOU AND YOU DID EVERYTHING IN YOUR POWER TO MAKE HIM HAPPY.