The guard caught the princess entirely by accident: she thought she was trapping a wild animal that had wandered into the palace and meant to return it to the forest. And so the princess might have avoided detection by simply waiting for the guard to leave before going about her business. But she was startled by being caught and slipped out of her guise. The guard was even more shocked than the princess by the encounter.
"Your Highness! Forgive me, I only meant to take a stray creature out of the castle—" the guard hastily bowed and averted her eyes, for the princess was not able to transform her clothing and was only wearing the canvas sack the guard had used to contain her animal form.
"Shhh! Someone will hear you!" the princess whispered. "And give me your cloak, it's cold out here"
"Yes, madam" the guard pulled off her cloak and handed it to the princess, who wrapped it around her shoulders. "Forgive my boldness, madam, but what were you doing, disguised as a fox?"
"First swear to me you won't tell anyone what you saw" The princess had regained her composure but was still frightened.
"I swear to it"
"Good. Now help me get back to my room before anyone finds us"
"Of course, madam. But first, let me go and call the other guard to watch. You would not have the castle unguarded, would you?" Seeing the princess's hesitation the guard added, "There is a place you can hide where no one will see you. I shouldn't be more than 5 minutes gone. Please, madam"
"Very well. Show me to your hiding place, guard." The princess gathered up the cloak around her and followed the guard to a dusty alcove behind a great tapestry.
"I will be back as soon as I can, madam." The guard helped the princess into the space, and left, draping the tapestry back over the princess. She gave some excuse to the other guard about needing to take care of an animal loose in the kitchen (which was almost true) and hurried back, glad for the leather armor that let her move quickly and quietly.
"Madam," the guard said, lifting the tapestry again. The princess stiffened at the noise but relaxed when she saw it was the guard.
"You will show me to my room now, guard" she took the guard's hand and stepped down out of the alcove, ducking under the tapestry.
"As you wish, madam." The guard walked the princess in silence through the halls. In truth, she was not in great danger of being caught at this time of the night. All the servants and the nobles had gone to bed hours before and even the earliest risers would not be up for hours after that. Still, the two women took the servants' stairs just to be certain they were not caught by anyone who might happen to leave their beds for whatever reason. They arrived at the princess's rooms quickly.
"You probably want to know what I was doing out like that" the princess sighed.
"Not if you don't want to tell me, madam, it was not my place to ask"
"No, I owe it to you. But come in first, it's not something I'd like to share with you standing in the hall for all the world to see and hear" The guard apologized and followed the princess into her sitting room. She stood awkwardly by the door while the princess went into her bed-chamber and dressed. She came out in a tunic, carrying a bottle of something and two cups. She set these down on the table and flopped onto the couch. "Go on, sit down. You've seen me naked, you can stand to see me lounge"
"Madam—"
"Oh, hush. What's your name, guard? I like to know a woman's name if she finds out my deepest secrets"
"My name is Sasha, Madam."
"Well, Sasha, I'm sure you know my name as well. You should call me that instead of saying madam all the time. Formalities are so tiresome." The princess picked up the bottle and poured it into the cups. The guard put her hand up to refuse. "Don't worry, it's not alcohol. I wouldn't want to interfere with your work"
"Thank you mad- that is, Miss Charlotte" the guard took a cautious sip of the drink.
"I am, as you know by now, a shapeshifter. This is a deeply held secret, known only by myself, the queen, and her midwife. I can only turn into a fox or a human. I am forbidden from wearing my fox form, which is why even the queen must not know what you saw. Do you follow?"
"Yes, Miss Charlotte. Does your father the king not know?" the guard sat stiffly on the couch opposite the princess.
"He does not. My mother has her reasons for not telling him, which she will not share with me. I suspect she fears he would question my legitimacy if he knew. Not that it would matter much, I'm not the heir. But it would be a scandal. A born skin-changer in the royal family! And shapeshifters being so rare, natural or not... there may be more than we think, just hiding as I do. My mother might be a shapeshifter and I would not know." She paused to sip from her cup. "Anyway. I like to go out at night as a fox and see what goes on outside the palace walls. I find nobility to be rather boring, and in human form, I would be recognized, and easier to catch" Charlotte chuckled.
"I am sorry about putting you in a bag, Miss Charlotte. Animals wander into the palace from the forest from time to time, and it's the guards' duty to catch them and either kill or relocate them."
"Well, it's good that you only tried to catch me! Imagine the scandal if you'd shot me with that crossbow of yours" the princess laughed. The guard's cheeks reddened.
"Thank you for trusting me, your highness. Another noble might have had me killed, and for your mercy I am grateful. If you are willing, I should return to my watch. The sergeant will be wondering where I am" She stood and bowed.
"I wouldn't want you to get in trouble for my sake, Sasha. If you need to go, then go. But I told you, you don't need to call me highness when we're alone"
"Yes, Miss Charlotte. Thank you," the guard bowed again and turned to go.
"Come back tomorrow night after your shift, Sasha"
"I don't think that would be appropriate—"
"That's an order, Sasha" The princess grinned. "And tomorrow, don't call me miss. It's just Charlotte"
"Very well. Thank you, Charlotte" The guard said and left, shutting the door softly behind her to make her excuses to the sergeant.