I saw that many people wish for and ending were the queen join the hero and Vice versa and i think that would be great (and i also want that) but i have another ending idea...
soo my idea is that when the hero ask the queen whats she fears, if you choose "being leave behind" (or something like that) at the ending of the run, the queen will ask the hero for a favor, asking him to remember her and continue her legacy, leaving her mace and crown together on the field.
like the quest line of lucatiel of mirrah from dark soul 2 where at the last quest she gives you her armor set and sword and asks you to continue her legacy (also, her armor can be found in dark souls 3 so the dark souls 2 protagonist did continue her legacy)
so that my idea... I hope I can contribute something and see this in the game, although I don't think it's possible, but at least I tried.