Slad, you freaking idiot.
Your auto-buff auto-debuff skill is literally capable of destroying entire kingdoms by your mere presence. Of course the King is not going to just dismiss you by default just because the Hero is here. Even if the Hero is "Necessary" to defeat the Demon Lord, your presence is just as frightening as a Demon Lord, and just by passively existing.
If you ended up considering the King your enemy, as well as his entire Kingdom, what do you think would happen? The only reason it doesn't happen is because you're too laid back and naive of a protagonist to just pull the trigger mentally yourself. From his perspective, while the Hero may be a specialist assassin to take down a singular target. You are a walking potential nuclear bomb, not in the sense of explosive power, but in the sense of being able to suddenly propagate highly destructive and impossible to block radiation if unleashed.
So of course the King is going to give YOU the royal treatment, and not the Hero. The Hero isn't even that special, he's just a specialized weapon. He has one role, you on the other hand, you clearly are far more of an all encompassing benefit. Hell I wouldn't be surprised if all the leeway you were given wasn't because He was the Hero, but because You exist.
Grow a brain Slad... And some balls. At least we know you have a huge dick, but have some balls, without that we'll also never get an Erotica tag on this thing.