Cait - Is pretty taken off-guard by the whole thing and feels sort of weird explaining it. However, she gives her a rough verbal description of how to do it, trying to avoid going into too much detail but successfully stating some things in a much too crude manner. She eventually scrounges some stuff for her and leaves her alone with it, hoping the girl won't need help.
Piper - Probably handles it the best of the group. She's already had to go through this with Nat not too long ago, so she's already got words of wisdom from before. She doesn't act weird about it, and makes sure not to discuss it more than F!Sole is comfortable with, but she just sort of shows her what to do on a clean pair of underwear and then leaves her to it unless she needs further assistance.
Curie - Handles it very calmly and just proceeds to sweetly explain it to her and tell the girl that it is one hundred percent normal. She tells her it is a part of the growing process, and it is a signal of the beginnings of bodily maturity setting in. She helps F!Sole find the proper supplies and gives her a thorough explanation of how to use them. Ultimately, Curie's descriptions are quite embarrassing, but it is very helpful in the end.
MacCready - Is terribly awkward and he just sort of does a lot of explaining that does not really equate to anything at all. He is not helpful in the least in the way of talking it out and making her feel better about it, so he just gets her some things and tries his best to give an explanation on how to do it, wracking his brain to try to remember how his wife did it before.
Deacon - Is outwardly cool, but on the inside, he's sort of freaking out. He does not have any idea how to handle this kind of thing, but he bluffs his way through it. He tells her it's normal and that she doesn't have to worry. It's just like every other bloodletting ritual that freaky cult religions pull, but it's nature's bloodletting ritual. Unfortunately, this way of explaining it terrifies her a little, so he has to tone back on the jokes and keep things a little more serious.
Codsworth - Is very elegant with it and reassures her, explaining it is nothing to be worried about and it is the beginning of her journey into womanhood. Of course, that made it much weirder than it had to be, but he means well. He quickly finds some stuff for her and tells her how to put it on, his healthcare protocols kicking in.
Hancock - Is a little surprised, but does not let it bother him. He handles it with that characteristic coolness with which he handles most things to do with F!Sole and he tells her it's all good, that it's normal, and every girl does it at some point. However, he does send Fahrenheit to find things the girl needs and when she comes back, he asks for a subtle rundown on what to tell the teen.
Danse - Bold of you to assume he does not almost pass out as soon as he is asked. He is standing there, hanging on by a thread as he tries to find the best explanation. Haylen soon finds them, fortunately, and she takes over for him. He leaves the room, heading outside to take the place of a soldier at watch. He needs some air...
Preston - Is awkward and pretty uncertain, but he tries to at least outwardly portray a sense of calmness in order to avoid freaking her out. He kindly assures her that she is perfectly fine and that it's normal for girls to do this. He ends up getting help from the nearest female Minuteman, and he asks her to explain it to the teen because he truly has no idea what he's doing.
Valentine - Is a little taken off-guard, but he handles it well. It does not surprise him, and he just calmly explains things to her before borrowing some things from Ellie until he can get F!Sole some of her own. He uses common sense and gives her a general explanation of how he thinks one is supposed to do it. He just waits outside the bathroom, listening carefully in case she needs him to come and explain things to her.
X6-88 - Just stares at her for a really long time before blinking and swiftly teleporting her to the Institute where he leaves her with some experienced doctors. He waits outside, not having any idea what is so severely wrong with her to make her start bleeding from such areas. Fortunately, he is given instruction on what to do in the future, and he figures out that it is perfectly normal.
Strong - Is confused and creeped out. He has never heard of humans bleeding from there and he asks her if an enemy shot between her legs. When she says that no enemy shot her, he is even more freaked out and he asks her why she is bleeding for no reason. He tells her she needs to eat raw meat or something and build her strength in hopes it'll make the bleeding stop.
Thank you to @yeslamblack43 for the request! 😊💙💛