Whitby Abbey

I think I may have found a Van Helsing-Mina dynamic pattern. Mina piping in to show that she knows something that Van Helsing just asked but wasn't expecting her to know.

First, it was when they first met and Van Helsing doubts her having "good memory for facts, for details?" as it's "not always so with young ladies", and then Mina going "I'll do you one better" and then trolling him a little with a sleigh of shorthand. Van Helsing praises her.

Now Van Helsing says

Then Mina doesn't say "actually, I have", she instantly proves his assumption wrong. She begins dropping Latin as much as he just did, and cites two contemporary sources on the philosophy of crime (though it's all now debunked pseudoscience) to back up her assessment on Dracula's mind.

I wish I could think of a way to maintain this banter in an adaptation but without a different subject matter, like the study 15th century history instead of criminology.

Anyway, Van Helsing ends up praising her again.

On a slightly different vein, another Van Helsing-Surprise Mina dialogue, followed by his praise:

“When does the next train start for Galatz?” said Van Helsing to us generally . “At 6:30 to-morrow morning!” We all started, for the answer came from Mrs. Harker. (...) "Wonderful woman," Van Helsing murmured.

I don't know if it's a teacher/student dynamic or teacher/young teacher...

Yes, it's so fun! I especially like the way she doesn't get all offended and interrupt to tell him "actually, I-" each time. It's a very characteristic detail. But just as important is the way she doesn't just meekly let his assumptions stand. Instead, she simply demonstrates her knowledge to him, proving that he really shouldn't make underestimate her. And he's astonished and impressed every time because he keeps doing it anyway and it's always fun to watch happen.

It's definitely a recurring detail. The shorthand diary, to an extent also Jonathan's diary, when she anticipated the need to not tell her things after she'd been bitten, when she surprises him with the news that she needs to come along with them, knowing the train schedule (though that was less focused on her from his part), the criminology discussion...

Not every single time I mention is as clearly expressed in dialogue with the exact pattern you pointed out, but in general we keep seeing him thinking she wouldn't know something or needs to be protected from something, only to then find out she's already thinking the same thing if not well ahead of him.

It feels like Van Helsing keeps defaulting to teacher/student or even father/daughter (in a paternalistic benevolent sexism way). But Mina just keeps quietly proving that no, actually they're equals. I guess that could lean towards teacher/young teacher (which actually, they literally were to an extent - Van Helsing was Seward's professor back in the day and before her marriage Mina was an assistant teacher) though it doesn't feel quite analogous to me for reasons I can't put into words.

As for the pseudoscience... I do think the best way to get around it would be to discuss more generally history or battle tactics. Focusing even more on Dracula's past and personality, and Van Helsing's own expectation of what kind of education a man would have had (he has to expect Jack to know it, after all, unless that is changed too) versus a woman. Unfortunately that loses the association of modernity, but I'm not sure what a better option would be to still get across the idea there while maintaining the direction of the conversation.