Board Thread:General Discussion/@comment-25555054-20150322061833/@comment-26037921-20150325031849

I believe that instead of Steven being neither Gem nor Human, he is rather both Gem and Human, allowing him to explore both worlds. Normal gems cannot fuse with humans, but someone who is already half human can fuse with another human.

I may be wrong, but there seems to be a dominant and passive role of fusions. Lapis was easily able to overpower Jasper when they were fused, and judging by Malachite's appearance and Lapis' control, Lapis seems to be the dominant gem of the fusion, much to Jasper's dismay. Pearl also seems to be the dominant gem of the fusion Opal, as she resembles Pearl more than Amethyst. Sugilite may have Amethyst as the dominant gem, as Sugilite has Amethyst's rash and lazy attitude, as well as her mischievousness. It is speculated that Garnet is the dominant gem of the very anticipated Pearl and Garnet fusion, but this is not confirmed until further notice.

I hope this helped!