Responses
He can be the secret identity type of ml, the servent, butler, knight that is pretending to be of humble background to hide who end falling to fl true self, they usually end up being hidden royal of the same country of the neighboring country or some duke.
I havent seen a sidekick (atm) or a bodyguard that seems to be a romantic interest be so bold with things like that, like flirting and such. Usually its the 'deny defend (and maybe even panic)' perspective, or the 'hide it until your last breath' typa thing.
Maybe he is the ML? Or 2nd ml? Maybe the relationship already has been warming up since their childhood and they both acknowledge it, or that he is joking around but eventually realises he likes her?
Back up back baack up im overthinking this lmao, its too soon to make that much speculation. But i kinda doubt shed end up as queen. Or becoming one and marrying into the royal family.