*A temporary reference till I get an official one*
Thunder Shine is pretty much so your average pegasus. He does have and ego to match that of Rainbow Dash. He once held several speed records at the Junior Speedsters Camp, only to have them shattered soon after setting them by Rainbow Dash. He holds a grudge against her for that, and swears he too will someday perform a sonic boom, even if it's the last thing he ever does. He has made several unsuccessful attempts thus far often making a fool of himself in the process. He works at the weather factory in Cloudsdale, and assists in weather control issues when they arise. Though he has a recent love interest, that has him considering moving to Canterlot.