I did the first pan drop & filter change on the 6R80 in my wife's V6 Mustang this summer, at 43K miles. The factory fill Mercon LV that came out was a dark wine colored translucent purple but had zero brown or black in it. It was however darker than the Kendall Versatrans LV fluid I put in to replace the drained portion of the factory fill. I got about 8 qts changed of the just under 12 qt capacity. So perhaps transmission model matters.
What I've read and seen is this transmission model has had issues early on in the Fusion. Hopefully they corrected those issues. I don't know whether it matters but the 2.3 Eco Boost is fairly powerful, maybe that puts more strain on the transmission, though it's not driven like a hot rod. The total factory fill is only around 9 quarts, not a lot. However in the end since it's super easy to change the ATF and costs $20/change using Motorcraft Mercon LV it's a no brainer versus a new transmission down the road from not changing the ATF more frequently.