Book 4 of the Cross-Shifter Series. Can be read as a stand-alone but might be confusing at the beginning for a bit.)
Being captive for years has soured Palace's outlook on just about everything. He sat in a rusty hauling container for weeks at a time, missing his big brother terribly, the only person he'd ever had in the world for so long, only to be sold to disgusting people who wanted him for illogical reasons.
Over that time, he became a killer. He didn't like it at first, but soon it became second nature. Besides, in his new world, where his original master only viewed him as another giant check, and those he sold him to saw him as their next horrible fetish until he ripped their throats out, he found little reason to behave favorably.
So, when a lion shifter crosses his path right before he is likely to be sold again, and actually treats him like he wasn't just a piece of meat to try and use, Palace isn't quite sure how to handle him.