In the short story "Bloodchild," Olivia Butler uses science fiction as a vehicle to explore issues relating to race and gender. In relation to the former, she deals with the possibility of love between different races. Indeed, Butler herself has characterized "Bloodchild" as "a love story between two different beings."
To be sure, the love that exists between Gan and T'Gatoi is by no means conventional. But perhaps that's the whole point. In detailing the unusual relationship between two very different beings, Butler is making a point about the problematic relations between white and Black people.
If there really is love in this relationship, then it is grounded in exploitation, as Gan is being used as a child-bearing entity. On one interpretation, this could be seen as a statement of the impossibility of interracial relationships without some degree of exploitation.
In relation to the topic of gender, Butler invites us to imagine what it would be like if a man had to go through the process of childbirth. This role reversal encourages us to develop a point of view that encompasses both male and female perspectives.
That Gan is the object of exploitation is crucial in this regard. Butler undoubtedly wants her male readers to identify with him in order to gain a better understanding of what it means to be a woman under the patriarchy. Gan's exploitation by the alien Tlics can be seen as a metaphor for how women are treated in a patriarchal society.