A mercenary, and of course it is

Byleth sighed as he gathered up his tent as the camp started packing up. They had apparently saved the heirs to the Three major powers in Fodlan, and had been invited to help the knights escort them back to the monastery. There was even another mercenary that had appeared and helped, and he recognized her as a mercenary he had fought and beaten before, and despite him having killed her previous group, didn't seem to take things personally enough for outright hatred, but she seemed to have some kind of ambition whenever he caught her looking his way.

Not to mention that he had died protecting the white haired girl by taking an axe in the back, before the green haired girl in his head (her name was Sothis, by the by) had chastised him for being an idiot before turning back time and letting him do it over, letting him deflect the axe instead.

https://www.pinterest.com/pin/sothis-in-byleths-body--22377329390202027/

'Would you rather be dead?' the annoyed voice of the girl in question commented on his inner monologue. 'In any case, I need you to help find my memories, and it seems we will be stuck together for the time being.'

Byleth nodded, keeping to his usual quiet demeanor. It helped in times like these, keeping strangers from thinking he was crazy as there was a voice chatting in his head. He really hoped he wouldn't have to deal with this for long.

A glint in the nearby grass caught his attention. "What's this?" He muttered to himself as he approached it, picking it up from the grass. It looked like a fancy oil lamp, but in need of some cleaning. He started rubbing it absently...