This, this, this . . .OK, the main character is a noble, so obviously he was one last week when the party visited the temple. Why didn't he say "I'm the Baron of Fubar, you must serve me!"? Make something up! There's no lack of 'white space' out there to fill in (notionally) to make room for why this was.
Especially make something up!
And so often, that something itself need be nothing more than a sketch or a hint. For instance,
Going back and retconning that the fighter's brother has been following the party for the last 3 months? Make sure he's trained in Stealth and don't worry about it, there are plenty of chances he could do this.
In my Traveller game, we know that one of the main PCs regained consciousness in a damaged cold sleep berth stacked in a warehouse in the domed city on the backwater world of Byron (this was the PC's introduction into the campaign), when the last thing she remembered was being in the naval hospital on Shelley (which was the only easy way to fit her PC gen backstory into what had already been established about the setting). How did she get from Shelley to Byron? Presumably in a cold sleep berth, but how did she get into that? And how did it become damaged in the warehouse? Subsequent events in the game have suggested some answers to the first couple of questions, though not complete certainty (the one person who actually knows is a prisoner of the Imperium); and the answer to that last one no one knows (the NPCs who might have provided answers mostly got killed in firefights or arrested by Byron's police force).
In real life no one seems to know when exactly the house I live in was built. (The planning documents I have seen don't appear to settle it, because they seem to treat what was really a build as if it was a renovation of the prior dwelling on the block; one neighbour probably knew the answer, but she had some cognitive issues when I met her and has died since.) That's effective "white space" in the real world, in respect of a house about 40 years old in one of the world's most effectively governed cities! Let alone a RPG world.