Rider
As Rin approached the horse, Sakura started to stroke her sister's hair, noticing the ice crystals forming in it. Clearly worried about her sister's health, she cast a spell to melt the ice, before jumping down out of Rider's arms and draping the coat the other Shirou had abandoned over her sister's shoulders.
“Be careful with this, Brown Senpai gave it to me", she said, clearly very pleased with the "gift" from her other Senpai.
Rider was pretty sure he'd just abandoned it in order to escape, but if treating it as a gift from her beloved Senpai made Sakura feel better, Rider was certainly not in any hurry to correct her.
Then, with her sister having accepted the coat, Sakura turned to address Rider, responding to her reassurances about the other Shirou.
“Rider, don’t worry, I’ll make sure he’s ok when we get home”, she said, before walking towards Pegasus and attempting to get on board, struggling to climb onto the horse.
Sakura gave out a sigh of relief at Sakura's acceptance of the situation, although she did wonder how she intended to make sure he was OK. Hopefully it would just involve asking Faust to send a few familiars. Seeing her master struggling to mount the horse, Rider walked over to her and lifted her onto it. Then, she climbed on herself, sitting in front of her master.
"Sakura, hold on to me", she said.
Shirou followed, and then Rin. The four of them were packed tightly onto the horse, only barely fitting.
"Hold on to the person in front of you tight, I will stop anyone falling", she said.
Rider waited for them to follow her instructions and get settled in place before she made Pegasus lift off. She flew steadily but quickly in the direction of Sakura's house, being careful not to do anything that might make the others fall. After a few minutes in flight, they arrived back at the house, and Rider landed in the front garden.
"OK, we're here", she said, waiting for the others to dismount before doing so herself.