Do any of the gems that fuse with Moon get hit with the negative emotions that they've been dealing with?
They do! It’s part of why fusing can be so difficult for Moonstone to even START the fusion dance. Either they’re pegged with an onslaught of emotions, or since fusion is about joining together, the other gem (or gems) in question will be attacked with that huge wave of negative emotions. There’s a very fine line that has to be passed- essentially a level of mental strength the participating gem has. The emotions come at them as a burst, and if they can handle the initial blow, the fusion can continue.
The Fusion typically can then have more control over the transfer of emotions, ie: they can control if they WANT to transfer emotions by touch. Moon can’t do that on their own, but in a fusion, they absolutely can.
Which is why Moon is on such a fence with fusion. They don’t like causing that level of stress on any gem, much less their team, but they also know once they get INTO the fusion, they will NOT want to get out. They like being able to control their empathetic powers, and not having to worry about absorbing emotions when all they did was put a hand on their teammate’s shoulder.
So far, they’ve only fused with those on their team, minus Spinel (Eon). I’ve drawn Sunstone, which is Moonstone and Fire Agate’s fusion. This one’s probably their second favorite fusion to use, if only because they’re alright with Fire Agate’s presence, and Fire Agate has a soft spot for Moonstone on the team.
Nuummite is definitely their favorite because they get along the best with Dark Fluorite (Benzarro), and this’ll be explained more in another ask I need to answer, but the two have a mutual thing they do where Dark Fluorite will let Moon transfer some of the negative emotions that are eating at their mind to Dark Fluorite. Obviously Moon helps when Dark Fluorite is suffering too much, but yeah they got this little symbiosis thing going.
Nephrite’s fusion is...difficult. Nephrite cares about his teammates, but isn’t affectionate ( at least, likely to get visibly concerned for the ) until they’re stranded on Earth. They get along, but just to work with one another. Nephrite rarely uses Moon’s ability to transfer his negative emotions out of him, and only uses it mostly get get himself LESS angry at Fire Agate or at the Crystal Gems. He bottles up sadness, which is actually a BAD thing to do when you wanna fuse with Moon. You HAVE to be open about how you’re feeling, or Moon won’t be ready to handle the OTHER emotions that end up absorbed when either does his thing or if you’re fusing with him.
Which blows because once they’re both fused, their fusion is scary strong. But yeah. Both of them aren’t a big fan of fusing with each other.