Here's a few pictures of as yet to be introduced characters. One of which (Lavinia) is seen briefly in the OP:
Spoiler:
Lavinia Liberus (ラヴィニア リベルス) Voiced by Ai Nonaka who also plays Emily
Martha Shubipauel (マーサ シュビーパウエル)
She looks awfully butch to me ^^;;
Ermengarde Yunihatz (Johannes?) (アーメンガァド ヨハニッツ)
Are those name correctly translated? I was wondering if Ermengarde's surname should be
Johannes as her character in 'A Little Princess' is Ermengarde
St. John? Johannes being the Germanic form of John and sounds more suited than ANN's suggestion of 'Yunihatz'.
As Zalas mentioned
here Lavinia and Ermengarde are characters in 'A Little Princess'. Lavinia Herbert is a spoilt rich girl who becomes a thorn in Sara's side and Ermengard St.John is Sara's sympathetic best friend in the book. A Martha (scullery maid) features in 'Secret Garden', also by Frances Hodgson Burnett. Maybe these roles foreshadow their roles in Strain...