I like
Hermione best of the three names. I don't think Ms Granger is a problem; she's a good character. And it is nice with
Theodora.
Did you go off
Rowena? I like that with
Theodora too.
Other names that come to mind:
FredericaElfridaSibyl /
SibyllaCosimaCharmianAgathaFrancescaLetitiaVerena