(Twilight): Two Princesses watch after Spike - and one of them is Princess Celestia herself.
She’s very busy - being Equestria’s ruler, teaching at our school and giving me private lessons - but whenever possible, she takes him for a stroll to the Canterlot Sculpture Garden or the Castle Orangery or the Botanical Gardens and tells him stories about Equestria.
As for the title, I’d never allow him to call her other than “Princess” or “ Your highness”.