Knowing the Ogre’s Heart by Lyonne Riley

After the death of his parents at the hands of human villagers, young Cragnorr the ogre was orphaned. Mia, only a child herself, rescued him from certain death, and has kept him a secret since. Now the silent, gentle Cragnorr has made it his mission to protect Mia, at any cost.
But when Cragnorr’s presence is discovered by Mia’s village, they’re forced to run. While the two friends must try to survive in the wilderness, their bond evolves into something else… until they accidentally wander into bandit territory.
Under orders from the bandit king, Cragnorr must fight in the gladiator pit for entertainment while Mia is forced to watch. Can they escape this terrible place, or will the peaceful giant become the vicious monster he is inside to save Mia?