His curiosity towards her siblings didn't lower her suspicious behavior at all, on the contrary; it only heightened her suspicion. 
On one side she was dying for some company. Traveling with undead hounds was safe, but she wanted somebody to talk to. 
One the other side she was suspicious of everybody other than herself and her Goddess. If she did find her siblings, whoever they were, she wanted to make sure she didn't bring any trouble their way. 
'Why would you help me? What do you two want in return?' she asked suspiciously. 
'Just so you know, I won't let anybody bring trouble to my siblings when I find them. Not even opponents like you.' she said sternly to the both of them. 'I haven't agreed to join you yet either.' she added.