Eugénie Danglars isn't like the other girls. Dumas makes it clear as day:
As for her upbringing, if there was anything to be said against it, it was that, like some traits of her physiognomy, it seemed more appropriate to the other sex. (53.50)
Oh, and she ends up in bed with Louise d'Armilly. So, we know she's not nineteenth-century French society's ideal woman. That's all well and good, you might be thinking, but what can I take away from that?
Here's something. Look at her parting words to her father:
"[I]n the shipwreck of life—for life is an eternal shipwreck of our hopes—I throw all my useless baggage into the sea, that's all, and remain with my will, prepared to live entirely alone and consequently entirely free." (95.21)
That's as strong a statement of independence as any character gives, and it seems that Eugénie's atypical nature leaves her free to make it. By putting those strong words into the mouth of a daughter who is supposed to be ultra loyal to her father, Dumas really puts them, and Eugénie, in the spotlight.