Pierce's call from here about what to do with you, not mine ...

I can't allow him into ANBU, being some wandering mercenary isn't working, mercenaries can't be trusted and can always be bought. Doesn't help the Empire bought most of them off and the rest got destroyed if they refused to join. Konoha isn't working this way, you're going to need to think of something else, especially since they can't find a background on this guy since you killed everyone. I wouldn't trust a guy I couldn't dig something up on in times like this.

Everyone: Mercenary backgrounds come with risk, Mercenaries can be BOUGHT, don't be surprised if people don't trust you because you have a very loose idea of 'loyalty'. Mercenaries are either bought or killed by the Empire, if you hope to join the rebel faction as a mercenary you have your work cut out for you.