i dont think jasper is obsessed with fusion she is obssessed with power but i want to state what i think happend and also why i think the diamonds corrupted not only some of the crystal gems but their own armies also i will talk a little about something that steven has that rose i atleast think didnt it is just one of his powers:lets go from the beginning which was the war for earth the diamonds sang their song now we saw how yellow diamond thinks of those smaller then her that they are minion just soldiers out to fulfil their duty that is atleast what i got from her speach with peridot, now im not sure about the other diamonds as they seem to be diffrent but for me it seems like yellow represents the more close minded diamond i personally think they are all very close minded but im not jumping into conclusions because the only diamond we saw is yellow diamond and well blue diamond but i didnt feel like i actually met blue with yellow i felt like i saw her opnions and her close minded personallty.
now lets jump a little to the war and the song first off i dont want to be sure its a song but it for now will stay an assumption why would the diamonds corrupt their own armies i think it was intentional it was to bring a more beastly side of them the more wild and instinctive side of the gems but i also think but not sure if maybe only maybe if lets say for example jasper combines with a corrupted gem my question is will she herself become corrupted maybe corruption is like an infection that can spread out meaning even if the diamonds dont sing again corruption isnt something that dissappears despite what i heard about fusion with it being seen as cheep tactic to make gems stronger on homeworld which is what jasper said but i myself am not sure how to take what she said but maybe if it comes from a homeworld view point maybe it is pretty hypocritical from a homeworld standpoint i think this is symbolic of what garnet said in keep it togther:fusion is a choice these gems werent given one.
maybe corrupted gems work the same they seek other gems maybe the seek the pure gems to hallow them out and make them corrupted, i think jasper will use the corrupted gems as an army because she wants to try and hallow out the pure gems and maybe thats what she is trying to do but what if and im not sure but what if a corrupted gem makes a pure gem hallow what if it is actually so it can make it self pure again what if fusion is just a means to end themselfs being hallowed out or being corrupted and they make a pure gem corrupted by fusion and use the fusion as a way to transfer its state to pure gem and the pure gem will be the empty vassel so the corrupted gem will become pure again and pure gem will hallow out to a corrupted gem, if this is the case i assume that jasper will use the corrupted gems to hallow out the pure and maybe then fuse with them but im not sure if it is really the case.
jasper obssesion with power the main ingredient and the fusion is just the seasoning fusion is just her way to feel strong because by herself she feels week kind of reminds me of pearl when she fused with garnet.
now lets talk about steven and how he can heal corrupted gems there is a way because i think there is one power steven has that rose doesnt that makes him not only the medic of the team but the savior of the corrupted gems his dream powers by what garnet said the corruption is the fabric of the mind being torn and steven does have his dream powers what if steven enters the mind of the corrupted gem and trys to tame it like you tame wild beasts and maybe he needs to heal its thoughts and help it in its mind and not physically cracked gems can be healed by the help of stevens spit but corrupted will need steven to go inside their minds and help them we see a few examples of this power of steven in the episodes: chille tid,super watermelon island,gem drill,the new lars and kiki's pizza delivery service in these episodes he interacted with others through his dreams and in some of these he controlled others well he was in their body i think this is what he will do when he trys to heal corrupted gems he will first control their bodies observing and learning their behavior and afterwards enter the minds and heal them i think each heal will take a bit of time as steven is learning to control this power also i assume most of times it would be like when he talked to the cluster what they said was very vague and it was very hard for him to read through what they said and help them.
now why did i say this power is something steven has and not rose dreams and sleep isnt something needed for gems steven is half human but of course it doesnt mean they cant as we can clearly see pearl had a dream but steven is half human so he is more familliar with the idea of dreams but he can also interact with others and connects to other pepoles dreams now im not sure if rose did or did not have this power what i assume is she had half of the power she could interact and control but gems and im not sure if she was as much of a medic as steven is although we really just see more and more powers as the series continues.
that is my thoughts