This might get eliminated, because I don’t actually know about Delaware’s situation specifically and am therefore working purely by analogy, but a good recommendation that deals (in part) with this subject is Chocolate City: A History of Race and Democracy in the Nation’s Capital by Chris Myers Asch and George Derek Musgrove. It goes beyond the scope of your question and even into the 21st century, but the first few chapters discuss race, slavery, and society in Washington, DC before the abolition of slavery in 1862. By 1830, free people were the majority of DC’s black population, and by 1860 (just before emancipation) they were almost 80%.

There are naturally some major elements of DC’s situation that don’t apply to Delaware, especially its urban nature, peculiar form of government, and political significance as the nation’s capital, but there are some broad strokes that could help you start to think about the issue. The free black community was economically stronger than in most of the South, and had some influence among white people, often challenging segregationist statutes through legal means (which slaves would have been and were unable to do) and occasionally receiving relatively favorable rulings, but the white population was for the most part just as racist and repressive.

Like Delaware, DC was a territory with a significant free black population, but not one that was fully free. One thing in society that this did not change (unsurprisingly if you know about Jim Crow and whatnot, or Northern society during this period) was white racism. It had a reputation among many white people for being a relatively good place for slaves, but they were obviously still slaves and suffered many of the same iniquities slaves in the rest of the South suffered. DC was segregated and heavily restricted civil rights for black people (a referendum to allow black suffrage in 1865 was overwhelmingly defeated), and major increases in the free black population (both relative and absolute) were often accompanied by increased repression and restriction of civil rights.

One of the things you could argue that did change, however, was the tension: often, a relatively strong free black community represented more of a threat to white society than a massive community of slaves. There were constant economic and political tensions between free black people and white people, especially white workers, with whom they coexisted on a much more equal footing than slaves and who often saw them as competition. Washington (like Delaware) was part of the South, and as I said before its Southern white population did not take kindly to what little economic and informal political power free black people did enjoy. One of the main motivations (among several, including of course anger at political disenfranchisement that continues today) for the retrocession of Alexandria and its return to Virginia, in fact, was the white inhabitants’ fear of free black political influence as their population grew. That fear, which comes up a lot in Chocolate City, was one of the major consequences of having such a large free black population.

However, despite the political and civil repression, the free black population grew steadily and significantly throughout the first half of the 19th century. And they weren’t doing too poorly for themselves, given all the systematic racism and oppression. There were thriving black institutions and even a very small black middle class, coexisting with slavery and the slave trade - while free black residents obviously supported emancipation, they lacked the political power to enact it, and white allies were severely outnumbered. While they didn’t have the overt political power to change laws or make significant decisions through the vote, DC’s free black community did work in other ways to oppose slavery and support civil rights, such as participating in the Underground Railroad, purchasing freedom for slaves, and providing education and other institutions for black people, as well as challenging segregationist law codes through lawsuits and activism.

I hope this helps, at least somewhat! Another, less related book might be An Example for All the Land by Kate Masur. It doesn’t deal with the issue of free vs. enslaved black people, and it’s also about DC and not Delaware, but reading it does give one something of a sense of the political and economic power built up by a historically established free black community that had existed for decades and how that affected the trajectory of Reconstruction, especially their resistance (formal and informal) to legal segregation, which had been a major avenue of black political agency in pre-emancipation DC as well. Again, DC was a city that barely (if at all) governed itself, not a full state with real length and breadth, but it might be helpful in outlining some broader effects of having a significant free black population like there was in Delaware.