Size differences just heighten so much about the relationship between characters.
Every time you’re alone in a room with someone, there’s an exchange of trust there. You both know you could do something to each other, even if it is buried under the surface, especially as that trust builds. Sure, there are definitely differences between different people and how much others ‘outclass’ each other based on physical capabilities, and subsequently, if they have tools to defend themselves. But we’re all still trusting (or not trusting) each other to some level.
When one character vastly outsize another, that changes. The giant doesn’t have to trust the tiny in the same respect. There’s not much the tiny can do to physically harm the giant. Why would the tiny stick around knowing the giant could harm them by some accident? How that trust is achieved and maintained (or just stolen, point blank) is so fascinating to me. There’s extra levels of complexity to address with such blatant power imbalances. Does one lean into it? Do they try to avoid it? Does the avoidance lead to accidents?
Ultimately, to me, size differences lend themselves to beautiful character driven interactions because trust has to be earned (or taken) on a much more extreme scale.