I would say that the theme is not "wanting" in either character. I would say that both Electra and Antigone share a very strong common bond through their dedication to and pride about their family honors. Electra is determined to mourn the lost of her wrongly murdered father, and Antigone is determined to ignore the edicts of her uncle Creon in order to pay homage to her dead brother. Both are very prideful and unapologetic about their families and their own right to behave in honorable homage to the dead.
From line 348, Electra says to her sister:
...You who, when I
did everything to take vengeance for my father,
never did a thing to help -- yes, discouraged the doer.
Is not this cowardice on top of baseness?
Tell me, or let me tell you, what benefit
I would achieve by giving up my mourning?
Do not I live?...And I hurt them
and so give honor to the dead...
Electra is certainly a girl proud of her loyalty to her dead father and critical of a sister who just seems to forget honor and pride of family and go with the flow.
Antigone is made to pay the ultimate price for behaviour she considers honorable, that she takes pride in. Creon condemns her to death for her actions, and, beginning at line 896, she says this about dying for her actions:
Still when I get there I may hope to find
I come as a dear friend to my dear father,
to you, my mother, and my brother too.
All three of you have known my hand in death.
I washed your bodies, dressed them for the grave...
Last, Polyneices knows the price I pay
for doing final service to his corpse.
And yet the wise will know my choice was right.
So, both Electra and Antigone defend and stand by their unpopular actions, supported by their firm beliefs in and pride about their families and honoring the dead.