Honestly, size difference is difficult, when it comes to determining how big something is, and then when you add an extra character into, then things will get a little tedious. Usually when I start off with the larger character, I'd try to assume the foot is bigger than the head, but that's discluding how they're positioned to where foreshortening takes effect.
Not to mention, the other character has to be in size as well to make them look snall compared to the large character. But even then there's something off when I add it all together and then everything spirals down from there. UvU;

Either a character's head is larger than the LARGER character, or the limbs don't match up if they happen to be kept the same way. Blegh, there's just too much to think aboyt when it comes to size difference and I wish there was some kind of guide or examples for me to look into to practice and reference on.

But this also means I'll be fiddling with Hyper stuff more often, and I bring up hyper since I wanna involve that into my future size difference drawings. F3c

So expect more but not limited to big butts and giant holes. ^v^