It Must Be Mine!

There is a valuable thing out there. It's one-of-a-kind, which makes it the greatest prize ever. That means someone wants it, just for that reason, by any means. Note it's not the artifact hypnotically seducing the person into wanting it. The person is just that selfish or greedy. Nor is it something earned; it's outright taken. It also doesn't count if someone steals it for the thrill of the theft, or to just show how good a thief he/she is. Either the thief has to want it, or he/she is stealing it for someone who does. Note that this rarely ends well, no matter whether the story is idealistic or cynical. That person stole something they shouldn't keep. In idealistic stories, it's too important to lock away. In cynical stories, it's too dangerous to try to lock away.