Working On African-American Genealogy

The lady, and good friend, that I share an apartment with is African-American.  She knew nothing of her family's background other than the names of her grandparents, that they were born in Louisiana, and that her maternal grandmother was described as a Creole and had lightly colored skin.  For her Christmas present, I gave her a 23AndMe DNA kit.  She received the results, and I started working on her family tree about three weeks ago.  My original set of names were of  11 people, Beatrice and her four siblings, their parents, two aunts, one uncle, the paternal grandfather, and the maternal grandmother.  It's been slow going, but the family tree now includes 111 people, tracing back to 1604.
   One difficulty is the "advantage" taken of young women of color in the American South.  Several women were single mothers and the father s of their children were often married men, or men of another race.  I have the names of the fathers listed on birth certificates, but there are several men who have those names in each community - unless something suddenly appears, I am at an impasse with those individuals.  The surnames are: Bell, Byrd, Jones, Michaux/Michot, and Tickled/Tickles.
    With the instance of the Creole grandmother, I was able to find her with her parents in an earlier US Census, and then found her grandparents in the 1880 Census.  In the 1880 Census, my Bea's great-great-grandfather was listed as a mulatto, his wife was listed as black, and his three sons (of 12 children) were listed a mulatto.  What was interesting was that the man was also listed as a "planter," which meant he owned at least 100 acres (it was 160 acres in actuality) - which was rather rare in 1880 in Louisiana.  So I had his surname, but with him listed as a mulatto, I felt that his father was white.  So I started looking into his surname....
    Then I found a fantastic posting on a DNA discussion panel - a great-great-grandson of the mulatto planter had received his DNA results, which showed he was a direct male descendant of a white, French settler.  This white French settler also had the same surname.  And in that man's inventory of possessions after his death, his slaves were listed by name and age.  In that 1816 inventory was listed the name of the great-great-grandfather, two of his siblings, and his mother.
   Luckily, the name of the French 3rd-great-grandfather is well known in French, Spanish, and American Louisiana.  That is how I have been able to trace the family back to 1604 in northeast France, and their connection to the Bouvier family of France/Switzerland that produced Jacqueline Bouvier, who married John Fitzgerald Kennedy.
    I was able to find the death certificate for the wife of Bea's paternal grandmother on-line, which gave me the names of Alice's parents.  I was able to then find her grandmother's grandparents - both born into slavery.  I have their names (Priest Tickled and his wife Charlotte), but I am still looking for their parents and families.
   I am still also seeking information regarding the 12 children of the mulatto planter, Luc De'Clouette.  I have been able to find four of them - Edouard, Hyacinthe, Luke and Peter. It was Luke's great-grandson who took the DNA test; and Bea is descended from the son Peter.
   Three nights ago, I found a copy of Luc's obituary on-line.  It stated that he had stayed with "his mistress"  after he was freed from slavery, and that during the Civil War he had protected her and the plantation from Federal troops. Later, it was "his mistress" that gave him the 160 acre farm that had been a part of the plantation.  In looking into this matter, I found that Luc's "mistress" was his older half-sister, sharing the same father.   Why am I not surprised at his "devotion" to his "owner"?