Warcraft doesn't sneak info into its tie-in material--it crams in as much as will fit and struggles to get the zipper closed. Much of the ‘Craft’s lore is covered exclusively in its 21 novels, six manga series, 11 comic books, and plethora of other side projects, only to be introduced into the games with little explanation. One of the best examples is Thrall, Warchief of the Orcs, who the games don't tell you started life as an orphan in a human internment camp.
According to the Warcraft Legends manga series, Thrall is rescued from beside the dead bodies of his parents as an infant and raised a warrior in a human prison camp. During his time there he develops human-like intelligence, which makes him both way smarter than the average Orc and desperate for freedom. Breaking out of his cage, he flees to the nearby mountains where he comes in contact with his own people, becomes a mighty shaman (wait...), redeems the Orcs in the eyes of the spirits (but...), succeeds Orgrim Doomhammer as Warchief (wait who...), and liberates his people from human enslavement. Yeah, and that's the simple version. Face the books yourself if you dare.