What do you think Ben and Holly’s dynamic and personalities look like?
Ben is usually calm, laid-back and chill and often the only brain cell left in dangerous situations. He is a good observer (in the woodpecker episode when he taught the chicks to fly by mimicking the flying poses despite not knowing how to do it himself), pretty handy and good at fixing things (like all the elves do) and a bit ambitious and a good animal tamer (I’m not sure is it the right term to use, but the successfully ride Speedy the Snail (one of the hardest to be tamed.) and forgives quickly (the elf games). But he can be a teaser (in the elf joke episode, with no ill intent), lose his temper quickly and occasionally dismiss fairies' abilities (such as magic and flying, but he learned from it and never did it as often). And talking about the “Ben’s birthday party” episode, he just asked Holly about his birthday card and either she remembered his birthday (I know the writers used that for plot purposes (reminding Holly to make Ben’s birthday card to get the episode going) but I feel that’s a bit insensitive from Ben’s side, so I would make it his flaw. And he's a bit of a power illusionist (in Superheroes when he cosplayed into Elfman, but his friends just called him Elfboy which is very humourous though)
Holly is outgoing, girly and sometimes pretty bossy. She has a kind personality and is naturally curious about everything (especially elf culture, like she always asks Ben what he’s learning at school or go to his school to experience herself). If she loved someone (familiarly, platonically or possibly romantically), she would be attached to them very much (eg: Nanny Plum, King Thistle, Ben, etc). And in my opinion, she’s one of the smartest fairies in the series (she nearly guessed Barnaby’s fairy disguise (she asked him “Have we ever met you before?” - simple to us the audience but considering how dumb the fairies are, this deserve applause). She compliments other people a lot (especially Ben). However, she is often overconfident of her own abilities (eg: her magical skills and the possibility of it going wrong), sometimes looking down on elven customs (but like Ben she fixed that quickly and may be one of the few fairies in BAHLK treat elves with respect (the other are the fairy kids and Mrs Fig)). She can be cruel with her magic when she’s angry (the elf joke day episode), and has a really scary death glare (the wand factory to Strawberry and to the Wise Wand 3000 in the new wand episodes).
I think both of them are optimistic, love adventure and cared deeply and concern for each other when one of them is in trouble, and treat each other as equals despite of class and race divisions (also deserve another applause)
Regarding to romantic shipping (when they are teens/ adults), they would fit into the “Childhood friends to lovers”, “Interspecies romance” and “Forbidden love” tropes ( considering the class and race difference, segregation and we never see a hybrid or a proper elf and fairy romance in the series )
=> Dynamic: (In the series) Very platonic and sibling-like (Ben and Holly treat each other like siblings that they never had since Ben is an only child and Daisy and Poppy are fucking hell spawns)