For the longest time I’ve had the idea that Trixie and Pierce are brother and sister, and recently I’ve decided on making them twins because it’s adorable.  
I mean, they both look similar, and they both have normal names, and I like to imagine that when Trixie first got into showmareship, he was there along with her being a fake fortune teller. His cutiemark is a safety pin, so he’s probably protective over his younger (and immature) sister, and would want to be there to look out for her, even becoming a fortune teller when he has no skills in that area just so he can join her on her travels around Equestria.
 
They became the dynamic and mystic duo of The Great and Powerful Trixie, and Pierce the Oracle.