Chanarach's attributes are brave/obedient.
In that same chapter, Hoid is shocked when he sees Shallan.
It's logical to assume that he recognized who he thought was Chanarach and he may have realized her parentage.
He later asks her
He then (definitely Allomantically) convinces her to Lightweave, before she realizes what she is doing and then stops. We have seen that spren are more likely to bond those that are around others that have been bonded, (Dalinar with Elhokar and Renarin, Kaladin with Bridge Four) so it seems even more likely that they would bond those that are around a Herald.