Lancelot

A group of adventurers found Lancelot hiding in the Death House in Curse Of Strahd, and he was adopted by the burgeoning paladin Ghalwin Forrester. He eventually ended up as a sidekick to Pack, proving useful in anticipating danger with his sharp senses in their quest to defeat Strahd von Zarovich. Gaining the nickname "Lance", he developed abilities as a fighter alongside his humanoid companions.

Lancelot learned to hold a silvered shortsword in his mouth when fighting dangerous creatures, and Ghalwin purchased for him a custom set of armor made by Yelena Arasek. In one of their adventures, The Pack found Ezmerelda D'Avenir waiting invisibly in the the Abbey of Saint Markovia, but relaxed when she clearly loved Lancelot. He proved to almost be a litmus test for people's intentions; noble people seemed to love the stout-hearted dog.

The legend of the warrior-dog grew around Barovia, and he was especially popular among children. He remained loyal to his master's word above all else, and Ghalwin grew increasingly worried that Lancelot might be killed by the horrors of Barovia. As they faced a potentially deadly fight against Baba Lysaga, the paladin asked Lancelot to guard Lydia Petrovna and their caravan outside of the swamps of Berez, and Lance steadfastly did his duty. 

Lance did not leave Lydia's side, even when The Pack did not return, but within two days they were approached by a member of the nearest witch-coven. Under threat of death and dismemberment, Lydia made the call to join her, and took Lancelot and the caravan. This ended up being a smart move; once in greater Berez, those bearing the Mark of Strahd did not attack the pair.

Lancelot lived for months in and around their swamp caravan, converted into a tiny shack with stripped wheels. They eventually reunited with Ghalwin, Ezmerelda, and the Heralds of Dawn, who were on a mission to get revenge against Baba Lysaga. This was successful, and the two moved to became new residents of Argynvostholt, acting as eyes to defend the mansion against interested interlopers. He was later picked up by the Heralds, and joined them on their adventure.