I don't think it's a matter of the ratties bonding with one over the other, but their personalities.
Ex: My rats have known me for 90% of their lives. My alpha male Gizmo, loves me and everyone else he meets thats human, very open to new company and attention. My other boy Gyro loves me only, any other human who handles him and he gets skittish. Nes my other boy is plain skittish, no matter if it's me or another person, this is due to his personality and the fact he has pink eyes. My girls, Zera and Lyra, they both love me but at certain levels. For instance Zera likes to hang with me, then hop off and do her own thing, sometimes ignoring me completely, Lyra can be more affectionate but like to do her own thing too.
For awhile I thought only Gizmo would like other human beings. However this was proven wrong after several more visits from my niece and nephew. The girls love my nephew, they kept climbing all over him, and my Gyro too who i thought would never warm up to other people. Only rat that refuses to relax around people is Nes. It's just something to work at if you want the ratties to bond with you and your partner, but it also depends on their personalities, at least that's my opinion under my circumstances. Good luck!