@pie if you're changing out piercings for the first time, that means that you're probably not totally healed up yet - they usually recommend to keep it in (but twist it every day) for like a week or so iirc (i'm fuzzy on exact length)
there will probably be a touch of blood doing the first swap of earrings/etc., but a tiny bit. probably more likely a scab.
@pie oh that's no problem then! i was thinking that you had like, JUST gotten your ears pierced and was going to worry about doing that on the train LOL