Bastet took the Stan's whistle from the ground and used her magic on it, before looking at your sister and you. “It was quite courageous of you two to defy a goddess. Foolish, but courageous.” said Bastet, with a happy smile. “Foolish, courageous and altruistic, since you tried rescuing someone that bullied one of you.”
Then, speaking specifically to your sister, she asked “Can I see your hands?” Thinking Bastet was about to give her the magically altered whistle, Emily complyed.
Instead, the goddess simply touched the palm of her left hand, making its invisible mark glow. When she broke the contact the mark stoped glowing, but stayed visible. It looked a cat's eye, exacly like the one on your right eyelid.
Emily and you were both left speechless, which elucted a light chuckle from Bastet. “This mark, along with its tween on your sister's eye, have two meaning.”
“TWO?!?” you both asked.
Looking at both of you, the goddess pursued. “The second one is linked to a slight alteration I caused. It mark you two as being under my protection and is why you could see me when no one else could.”
“And the first?” You wondered aloud.
“This is primarily a FriendMark, directly linked to SoulBranding. When the one making your SoulBrand is someone dear to you, like your bestfriend or a parent, chances are you both are going to inerit identical FriendMarks. Peoples sharing a FriendMark can always feel which way and how far the other is.”
Then, looking direcly at Emily, she added “And in your case, it also unlock your ability to do magic, making you the first magical human since… Since long before my own birth, now that I think on it!”
“What kind of magic do I have?” naturally asked your sister.
To which Bastet answered “That's something not even the First can say, you have to discover it yourself” before disappearing.