Katja/Usko headcanons(v. human no more + afflicted);
It is supremely difficult to separate Katja from Usko and vice versa; she is fiercely protective and probably the more dangerous of the two. Usko is similarly protective but takes a more pacifist take to conflicts. Where Usko would rather run than fight(which typically means picking Katja up and then fleeing), Katja will fight tooth and nail if someone means her or Usko harm.
Katja may not have been the breadwinner of the two, but her previous experiences(helping around the farm and helping Usko carry his work) has left her with substantial muscle mass. She is by no means SUPER RIPPED, but she can wield a Kirkhammer without too much difficulty.
As a human, Usko stands at about 5' 5". Katja is about 5' 6". His slow transformation does little to alter this, until it reaches its appex, where he is then about 14' at full height.
Usko is definitely the more calm of the two; Katja has very little caution, and will speak her mind regardless of the consequences. It is perhaps a good thing then that a majority of what she says is in Finnish.