Rider
After purchasing the clothes for the new servant, Sakura brought them all to the food court, where they purchased whatever food they wanted and, then, sat down at a table in the corner, as far as possible away from anyone who might want to listen in to their discussion. Then, when they had taken their seat and begun to dig in to their food, Sakura began to speak.
Rider found herself somewhat peturbed by Sakura's somewhat-unhealthy emphasis on the danger of vampires, particularly given that she knew there were far more dangerous things here than simply vampires. Then, Sakura began to talk about her magic. Once again, Rider was surprised and a little concerned with her explanation, the surprise clear on her face when Sakura mentioned "bug magic". Not that she found it impossible that Sakura could learn such magic, it was, after all, part of the Matou magic that had been burnt into her body, but she was surprised that Sakura would put enough effort into learning to use such magic, or talk about it as if it was her main ability.
Then, with Sakura finished, Jeanne spoke up. Rider frowned momentarily at the mention of her obtaining her magic resistance through "faith", after all, she was highly suspicious of the gods and of anyone who had such faith in them or used them to gain power. Still, ultimately, she saw no reason to hold it against the girl. After all, as awful as the gods were, and as bad as some heroes could be, there were still many perfectly-nice heroes even in her time, and Jeanne seemed like a nice person, so she wasn't going to hold the source of her power against her. And, given that it meant she would be immune to Rider's Mystic Eyes, it was extremely helpful for their battle stategy.
Continuing, Jeanne began to explain her Noble Phantasm, a representation of her battle standard that allowed her to protect herself and her allies from harm. Again, that would be very useful, especially when coupled with Rider's ability to quickly withdraw Sakura from any dangerous situation using Pegasus. Overall, Rider was fairly impressed with Jeanne's abilities, they were certainly likely to be useful in helping her to protect Sakura.
Rider wondered if she should speak up next, to explain her abilities to Jeanne. However, before she could do so, she felt Shirou tugging on her arm, obviously trying to get her attention. Turning to him, she noticed him motioning that he wanted to go and talk to her in private. Momentarily, Rider considered whether she should go with him. After all, this was an important discussion, and she didn't want to miss something that would be useful later. Ultimately, though, she knew that, if Shirou wanted to talk to her, it was probably something to do with Sakura. And, given how she had been acting over the last few days, she suspected he wanted to discuss his concerns with her.
Sighing, Rider realised that she couldn't simply ignore him. If he had concerns about Sakura's well-being, then she needed to discuss them with him. For a moment, she considered how best to excuse herself, before realising that she had already drunk much of her drink. Taking the cup and finishing it off, she spoke up.
"Sakura, I'm just going to go and get myself another drink", she said, getting up and leaving the table.