Before you call lore inaccuracy, there is a scene in the first episode with Sugilite where pearl says, "You've been fused for to long, you're losing yourself."

To which Sugilite replies, "I am myself, so you better get used to me." Also, we don't know much about fusion at this time. So, judging by the Sugilite thing, maybe this can happen? Who knows? Anyways, it makes an interesting story (And on the off chance this becomes really popular, I may actually apply to work on the show if CN is hiring. Probably not, but if this does become popular, I'll give it a shot.) Anyways, enjoy.

The corrupted gem poofs. Steven bubbles it. "Nice job Steven," Opal smiles.

"You guys were great!" Steven smiles, "but haven't you been fused for a while? It took us a long time to get this one poofed."

"Yeah," Opal smiles, "we should unfuse." Opal begins to unfuse, but she stops. "No!" She yells.

"Are you guys OK?" Steven asks.

Opal smiles at Steven. "I'm fine," she smiles. She glows with magical light as she begins to unfuse again. "Stop it you two!" She yells.

"You... two?" Steven asks, "is this a fusion thing I don't know about?"

"It's nothing," Opal smiles as she stabilizes, "you head on back to the temple, I'll meet you there."

"Are you sure you don't wanna unfuse?" Steven asks, "you're acting kinda weird."

"I'm fine," Opal lies, "I'll be there in a bit."

Reluctantly, Steven heads back to the warp pad. Opal looks around, the corrupted gem was in a fairly shady forest, but enough sunlight shines through the colorful tree leaves as they dance in the air for the river nearby to glisten in the light.

Opal sits at the edge of the lake and stares at her reflection.

"Why can't we unfuse?" Pearl asks.

"I don't know," Amethyst replies, "try again on three. One... two... three!"

Opal begins to unfuse, but she stops again. "Will you two cut it out!" She yells.

Pearl and Amethyst are to shocked to reply, Opal has become self aware, forming her own conciseness. "You listien and you listien good," Opal demands, "I'm not going anywhere, I won't be torn apart again. I'm here to stay."

"You can't do this," Pearl warns, "Steven's gonna catch on."

"You're right," Opal smiles, "he's a good kid you know. That's why we gotta keep moving."

Opal begins to move away from the warp pad.

"Pearl," Amethyst whispers, "what about Garner's future vision?"

"Why did you think I didn't bring it up?" Pearl replies, "that's our only chance."

"How did this even happen?" Amethyst asks.

"We were fused for to long," Pearl replies, "but that's the only possible cause I can think of. For now, we just have to wait..."