I'm asking about homosexuality between the slaves themselves or even between the slaves and the slaveowners. Are there accounts of this happening? (I'm sure there are.) What consequences do the slaves face? The slaveowners? I know accounts of (female) slaves being encouraged to have relations with (male) slaveowners to "move up" but would the same thing be encouraged of homosexual slaves?
This is a very interesting question, yet one that I feel is probably going to be difficult to answer for a number of reasons. First, I think like any social or feminist history of 19th century slavery (I'm using these terms as specific descriptors of established schools of historiography) you're going to have a hard time digging up primary sources that speak to this. Homosexual relations were seen as scandalous and taboo even as recently as 20-30 years ago, which leaves a historian with very little to draw from when examining diaries, oral histories, or even periodicals. People who were slaves that reflected on their experiences later in life might have spoken out about hetero rape, yet any connection to homosexual relations, even non-consensual, might have been seen as shameful or embarrassing. The fact that it doesn't come up very often in the primary sources seems to lend some weight to this hypothesis. As far as consensual homosexual relations among the slaves, this same reasoning could be applied, for the social stigma on homosexual relations in the late-19th and early-20th centuries would have kept many men and women from talking about this (at least in public). Second, since sex acts are traditionally private or concealed from public observation, there wouldn't be a lot of 3rd party witnesses to write about it. If someone suspected that homosexual rape or consensual homosexual relations were occurring, they MIGHT have written in a diary or letter about it, yet likely would have been shy about speaking about that in public. Some good, honest research into the subject might turn up evidence in letters or diaries (indeed, there may be a book or thesis out there that covers this that I'm not aware of), yet I wouldn't be surprised if it proved to be difficult to find enough primary resources to back up a thesis on the subject.
I have one incident that I know of; Harmen Van Den Bogaert was a well off dutch slaveholder in New Amsterdam and was arrested for sodomizing his slave. Interestingly, his slave stayed with him when he broke out of jail twice, suggesting that it may have been a consensual relationship. I first read about this in Russell Shorto's "The Island at The Center of The World," but you can find a pretty good account at this web article: http://www.dailykos.com/story/2011/06/09/983560/-Harmen-van-den-Bogart-the-price-he-paid-for-same-sex-love-in-old-New-Netherlands