Well, I took two scenes where Steven is in the same place compared to Alexandrite/Sugilite and then put the two together, not counting the hairs Alexandrite goes on Sugilite's nose.



I think that the more the personalities of the gems combine and the more they have a good relationship the more normal the fusion will be, the less the personalities of the gems combine and the less they have a good relationship the less normal the fusion will be, examples:



Sapphire and Ruby love each other a lot, which makes their fusion perfect.



Jasper and Lapis both have a bad relationship and their personalities don't combine, so Malachite is really weird, so much that she was classified as the most monster-like fusion of all of 'em.