Hmm I haven't decided for her breathing style..I was going consider Metal breathing or something of that kind but I'm not sure if it suits her..
How she met Genya? Well they met at the butterfly mansion! When Marri doesn't have any missions she usually Will help out the girls there including taking care of other slayers, at that time when Marri accidently bumped into him making her hairpin that she wore at that time fall and thus broke..she was a bit upset about it..but when she was assigned to take care of him she was a bit confused on why he wasn't talking and his face was so red when she asked him things like "do you feel pain anywhere else?" Or ask if he had his meds and most importantly his food offering to eat it with him if it means he'll eat something.