The Return of Night Mare

That evening, Twilight was cleaning up the library. She had told the foals to help Spike clean up. They all did a good job putting the books on the shelves, but they didn't do a good job of sorting them in alphabetical order. Suddenly there was a knock on the door.
Now who in all of Ponyville could it be this late in the day? She opened the door, and saw Prowler. Looking a lot less tense than when she last saw him.

"Oh! Prowler! I wasn't expecting to see you so soon."

Prowler smiled. "Yes. It's quite amazing what 12 hours of sleep will do to you."

Well that's certainly a relief. Twilight thought. "So are you going to take the night off?"

"Unfortunately not."Prowler explained. "There's still a lot of paper work to be done after what happened after this morning. I won't be in the field, but I will certainly be in the office."

"Oh, well be sure not to overwork yourself." Twilight was a bit disappointed. She was hoping Prowler could get some slack after such a long work day before.

"Speaking of which, do you have any spare could you don't mind parting with?"

This seemed like a strange request, but Twilight went back to her collection to take a look. "I'll see what I kind find. Anything in particular?"

"Something lighthearted." Prowler stopped to think for a moment. "And the longer the better."

As Twilight sorted through books that fit the description, she couldn't help but wonder why Prowler would want a bunch of books all of a sudden. After all, it wasn't like he could read them while he was working.
"So, do you plan on taking these to the detention center?" Twilight asked.

"Of course." Prowler replied, as if it were only natural."

"Hmmm." Twilight took the last few books and put them into a satchel. "Mind if I come with you?"

Prowler chuckled. "I guess that's a reasonable request."

So the two ponies continued on through the night, towards the detention center. Prowler carrying one satchel, and Twilight carrying another. It wasn't very often that Twilight got to walk around Ponyville this late, at least not unless there was some emergency. And despite Twilight's concerns, she found the experience surprisingly comforting.

When Twilight and Prowler entered the solitary confinement wing of the detention center, the entire feeling changed. There was no moon, and no stars. Just a seemingly endless hall. Neither Twilight nor Prowler said anything as they walked down this long hall. Twilight tried to think of something to say. But every time she thought of something, she stopped herself. Then they rounded the corner.

When Twilight saw Night Mare, she was a bit surprised. She remembered Night Mare as a miniature version of Nightmare Moon, albeit with yellow eyes instead of Nightmare Moon's bright blue ones. This unicorn, although she looked the same physically, somehow appeared much smaller. Her eyes weren't conniving like Twilight remembered. Although Night Mare's eyes were still very eerie, they seemed more cautious and ashamed.

"And what brings you here this fine evening?" Night Mare's voice was soft.

Twilight focused her attention on Night Mare. She was trying to watch for any signs of magic, especially mind altering magic. After all, Twilight didn't get to see much of Night Mare's original interactions with Prowler on the bridge. So she had to be prepared for anything.

"I brought you something." Prowler calmly unlatched the satchel on his back.

Twilight was taken aback. She wasn't expecting Prowler to be so relaxed, especially compared to how tense he was that morning. Although Twilight was confused, she took the hint, and unlatched the satchel on her back. Prowler picked up both satchels, and dropped them down a small shoot next to Night Mare's cell. The satchels landed in Night Mare's cell, and she started going through the contents. After she looked through the satchels, she very curiously looked at Prowler.

"What are these for?" She asked, with an eyebrow raised.

Twilight was half expecting her to reject them.

Prowler was not phased at all. "They're books, obviously. To keep you occupied. I'm not going to be able to visit you very often. My duties as chief of security keep me very busy. Especially at night. But I thought maybe these could at least make things easier for you." Prowler smiled. "After all, it's hard to see the fear of ponies that only exist on paper."

Night Mare seemed incredibly shocked by this explanation. But after a moment, she let out a dark little giggle. And then, for the first time since she was taken in, she gave a heartfelt smile. "I appreciate the gesture."

"Before I go," Prowler paused. "Do you see anything today?"

Night Mare's eyes glimmered. She smiled. "Not today."

As Prowler and Twilight went back down the hall, Twilight felt she understood. Night Mare clearly wasn't trustworthy. And there was certainly no reason to think letting her go was a good idea. But she understood what Prowler meant when he said she didn't seem like a bad pony.

Later that night, after Twilight returned to the library, Twilight got out her quill and paper to write a letter.
"Dear Princess Celestia,

Today, or more accurately tonight, I learned that there are ponies out there who can do terrible things. You don't have to forgive them, especially not right away. But that doesn't mean you should act out at them in revenge or anger. If you're willing to listen, and keep an open mind, both parties can come to an understanding. You don't have to become best friends, but you can still learn to understand each other. And after coming to an understanding, that's when both ponies can start working together towards forgiveness.

Your faithful student,
Twilight Sparkle"