Thunderlane wanted to be happy that his little brother finally got himself a special somepony. However, Rumble's some "pony" wasn't really who he expected. For one thing, he was a dragon. Another thing was he was still roughly half Rumble's size.
Meet the most cynical pony in Canterlot, who under the latest Princess' orders, moves to Ponyville to meet up with the Mane Six for his own quest to find friends. Many Swear words ensue.