River Rock is the only foal that any of the Pillars of Equestria had. After Rockhoof and Mage Meadowbrook quietly get married (with everypony in happy attendance, of course), it didn’t take long for River to make his way into the world. Growing up, he loved to sit for hours and listen to his father’s tales of the past, or help his mother with her latest feast. He is fascinated by the many adventures his parents and the other Pillars had (all of whom he lovingly referred to as ‘aunts’ and ‘uncles’). Studying under Twilight Sparkle and Stygian also helped build River’s love of the history and lore of their world. Rockhoof passed down every story he could remember, and took River on most of his travels. However, despite all the knowledge he’d gained, nopony could stop the fading light in the Pillars. As Starswirl becomes weak, it becomes apparant that his magic, being the core of the Pillars connection, is what is keeping them alive. Once gone, they would be as well. River does look back on this time with some relief that he was able to prepare for his parent’s passing and say goodbye.
After the Pillars all pass, River is left alone at fifteen. Stygian respects the colt’s space, but keeps a close eye on him as he finishes his last year of study, then heads towards the woods to build himself a cabin, set perfectly between Ponyville and Whitetail Woods. Having learned quite a bit about the wilderness from his parents, River Rock found himself secluding himself away between the trees. Stygian visits often, sometimes accompanied by camping shop owner, Double Diamond. The two stallions prove imperative in helping River through his grief and adjustments to a life on his own. About five years pass, and River takes over the role as park ranger for the eastern region of the Smoky Mountains. The saddened colt from a few years ago seemed to have nearly transformed into a new pony - a stallion full of life and excited to share it with his friends. He makes his living from taking groups of ponies and other creatures on guided tours through the woods, including ziplining and rafting. Each tour, of course, is rich in various tales from the region. River also helped Twilight ensure that all of Rockhoof, Meadowbrook, and the Pillars’ stories were taken down in writing, so they could be enjoyed for many years more.
As he integrates Ponyville and its citizens back into his life, River is a common sight in the village. He is friendly and upbeat, if not a tad sarcastic at times. His passion for nature and the earth itself often leads him to butt heads with Sandstone Pie, up-and-coming paleontologist. The two are rather stubborn, but when working together, they have made some pretty impressive discoveries in the twisting, winding paths of the forest. While she’s not in the running for Princess of Friendship, Sandstone also helps River as he tries to get more comfortable making friends again. Though her advice can be coarse, brash, and slightly unhelpful at times, River admires her determination and fortitude, though her attitude can get a tad grating at times. Though he walked through a few difficult years, River Rock is intent on making sure the accomplishments of the past are still recognized, the areas where one can learn are being taught, and making his parents proud.