Steven Universe
Fusion is the process in which the hard light forms of two gems are mixed together by choice to create a new form, and a new personality of the Gem. It can only be achieved by perfect synchronisation of two Gems. Steven is an exception to this rule - because he possesses Pink Diamond's Gem in his body, he is capable of fusing with both humans and Gems, for example, with Connie to form Stevonnie.