I've added Mortimer's bio in the RG and copied it below. What do you think?
Possibly he wanted to keep a low profile, so close to his home country of Cheliax, and only now decides to help out the caravan that is wrongfully accused.
Appearance and personality
Carrying himself with grace, Mortimer Perdergast is obviously of noble descent. He dresses in simple but high-quality clothes, which are fashioned to hide the thin armor underneath. His angular features are not particularly handsome, but his attention can be inspiring or fearsome, depending on his mood.
Mortimer is a thoughtful man, looking at different angles to an issue before making up his mind. He is very comfortable in the spotlights, but prefers not to be seen doing any dirty work.
Bio
Mortimer is originally from Cheliax, born to a minor noble family. As the third son he received a fine education, eventually studying the laws of both his home country and those of many others.
It was not unusual for students of law in Cheliax to bend and break those laws; after all, if caught, what better proof of his education than to defend themselves successfully in court? Mortimer honed skills that some would consider unethical, including stealth and thievery.
What made him leave his family and home behind is something he never speaks about, but at some point he dropped his family's name and left Cheliax. He worked as a barrister in the surrounding countries for a while before joining a caravan from Elidir to Andoran one fateful day...