biological father and Hen's ex, Eva, filled for custody of Denny when she was
released from jail, because she thought that having Denny will
make Hen come back to her and was envious of Hen and Karen's life
together. However, in season 2 episode, "Awful People ", Eva
has an overdose, which puts her back in jail. Denny's biological father,
Nathaniel Greene, had no idea he was the father of Denny until Eva told him.
Although Eva initially attempted to manipulate Nathaniel into suing for custody
of Denny, he met with Hen and Karen, saw how happy and well-loved Denny
was, and stopped fighting for custody.
Hen and Karen worried about Denny adapting to having a sibling, but he clearly adored his baby sister Nia.