When Fluttershy first adopted Anthea, after seeing her use a spell on a Manticore to calm it down and escape, she understandably assumed the filly to be rather brave, or at least not as shy as it turned she was.
Perhaps due to her kind, caring demeanor, Annie wasn't very nervous around her or her house. Nor was she nervous with the other fillies at the orphanage, the had known them for as long as she can remember after all. But Fluttershy couldn't have predicted what would happen when she took her out to go visit Crystal Clarity and Turquise Blitz, Rarity's kids about two weeks after she adopted her.
There wasn't necessarily a reason for Claire and T specifically, other than them having availability at the right time.
Before they even arrived at Rarity's place, Annie was already pretty nervous. But Fluttershy understood. This was a fairly new environment for Annie after all. She had explored some of the area with the other orphan fillies, though they never did go into the center of Ponyville, nor the area around the Carousel Boutique.
Fluttershy knocked at the door, arriving right on time, with Annie hiding behind her tail.
"Oh, don't worry, Annie. We're just here to meet some friends. Rarity and her fillies are a few of the nicest ponies I know."
Though, this didn't make Annie much less tense.
Rarity opened the door, causing Annie to hide further in Fluttershy's tail.
"Oh, Fluttershy! Long-time no see!" Rarity exclaimed with a hug. She then looked to either side of Fluttershy. "Now, where's the little Annie I hard about?"
Fluttershy looked back to see Annie trying her best to conceal herself entirely behind Fluttershy. Apparently, she was doing a good job.
"Hey, come on Annie. this is my friend, Rarity. Don't worry. She's very nice."
Annie popped her head out from behind Fluttershy, and seeked around for a second, before looking roughly at Rarity.
"...Hi..." She said, very quietly.
Rarity crouched down, but didn't walk any closer.
"Hi, darling. Do you want to come in and meet some ponies?"
Annie replied by going back behind Fluttershy.
Rarity stood back up.
"Well, she's rather shy, Isn't she."
Fluttershy looked back to see how Annie was doing again.
"Even moreso than I was, I think." She commented.
"Well, what's your call, Fluttershy?" Rarity asked.
They had both cleared out an hour of the day for the meeting, which Fluttershy assumed would go a bit better. Since everypony she had seen Annie interact with, it had gone much better.
"Let's go along as planned, and see if things get any better as we go along. Maybe she just needs to warm up to them."
"Alright then, I'll go get the kids. You two can make yourselves right at home."
Rarity said as she went inside and upstairs to get Claire and T.
Fluttershy slowly walked into the building, for Annie's sake. As she walked, Annie stayed glued to her. When Fluttershy sat down, Annie sat behind her.
Rarity came down with T and Claire a few minutes later.
T ran up to Fluttershy and said "Hi miss Fluttershy!" He looked around the room. "Mom said you were bringing somepony," T said, confused that Fluttershy had seemed to come alone.
"Oh, I did. She just needs to come out and introduce herself," Fluttershy looked back around to Annie hiding behind her. "Come on, Annie. Introduce yourself."
Annie poked her head out just enough so she could see the green blur that was T.
"...Hi..." She said again, only a little louder than last time.
"Hi. My name's Turquoise," He introduced. "What's your name?"
"My name's... Anthea." She said about as quietly as last time.
"Nice to meet you, Anthea." T stepped aside to let Claire go aside him.
"Hi there Anthea. I'm Claire, Turquoise's sister." Claire introduced herself.
"...Hi Claire." Anthea quited back down.
Fluttershy wrapped her wing around Athea, which made her a bit more comfortable.
"Why don't you three talk about yourselves a bit more? Like how old you are and such?" Fluttershy recognized that Annie was probably more comfortable with just talking for now and leaving any actual activities for another time.
"Well, I'm 5, nearly 6," T said. It was only a month or so from his birthday.
"And I'm 11, almost 12." Claire's birthday was only a few weeks from then.
"And what about you, Annie?" Fluttershy asked. She was ure that if Annie just gave it a try then she be more open and comfortable about it.
"...I'm 5..." Annie squeaked out a little louder than last time.
"And what do you like to do?" Fluttershy also asked.
"...I like to go outside and hang out with mom's little animals..." Annie talked slowly, but she was getting better.
"I'd love to gout out and do that too, but we're inside all day helping mom with work," T explained.
"Yeah, but I like it. I sort her jewelry for her and you know how I like doing that." Claire said.
Annie went back behind Fluttershy while they were talking. So much for that progress. Fluttershy tried to get her to come out again. "Come on dear. They're talking about what they like. Just like you."
This didn't help. all that much. It seemed as if Annie just wasn't going to come out again.
"Well, that's not very good," Fluttershy said to Rarity. "I was hoping she'd make more progress today." It's not like Annie hadn't made any progress, she was talking to T and Claire. But it just wasn't what Fluttershy was hoping for.
"Well, she did do pretty well if you ask me. I think if she gets together with more fillies I'm sure she'll be fine." Rarity said. And she was right, Annie hadn't been with more than just a few ponies for her entire life so far, so meeting new, unfamiliar ponies would definitely make her nervous.
"Yeah, that's true. I'll probably take her home so she doesn't have to keep going like this since she clearly isn't into it yet. but let's do this again sometime. Maybe next time, T and Claire can come over to my house?" Fluttershy proposed.
"Yeah, that'd be wonderful. I'm sure T and Claire will like that very much."
Fluttershy stood up, and Annie immediately glued herself to her hind leg. "Well, it was nice meeting with you. Let's arrange that next meetup sometime soon." Fluttershy said as she walked to the door.
"I'll be sure we do this again," Rarity replied.
Annie just needed more time to get to be comfortable with other fillies. But for now, she just needed a break from all the stress.