"We're just close -- just going through her mom's passing and grieving together," he said.
Gordon, 22, and Bobbi Kristina, 19, seemed to confirm their closeness on Twitter, while neither confirming nor denying the reports that they were dating.
"Yeah, we got a little closer and what!!!" Gordon wrote a few days after posting a photo of the two of them smiling.
That was followed by "All the haters that don't know us or the real story can't unfollow me. I don't give a f**k." "I've proved my loyalty to her and the Houston family. I don't owe any of you anything. Ha, I don't even know y'all haters."
"Some ppl [people] have no lives so they gotta be in ours," he added.
Gordon also made it clear that the two are not related by blood.
"For the stupid ppl out there, she gave birth to 1 child. And she trusted me with EVERYTHING!!!!!!!!!!!!!"
He added, "She called me her "God Son." I swear some ppl in this world act like they don't have a brain …"
As for how Bobbi Kristina is handling her mother's death, Gordon wrote, "Kriss is doing really well. I've been so happy with her strength."
Bobbi Kristina posted one of Gordon's tweets on her Twitter page, along with tweets from their supporters. "@ndgordon it's no ones business what you and @REALbkBrown do. If people don't understand, that's their problem. Do what makes you happy," one person wrote.
Hollywoodlife.com recently reported that the couple were seen making out in a Target store near their home.
Gordon was "like a son to her," her brother, Michael Houston, told ABCNews.com.
Image Credit: Twitter/RealbkBrown
According to sources close to the family and a TMZ report, Houston invited Gordon to live with her more than 10 years ago after learning that his birth mother could no longer care for him.
Bobbi Kristina did not discuss her relationship with Gordon in her first interview since her mother's death Feb. 11. Instead, she focused on her mother.
"I'm doing as good as I possibly can," Houston's only daughter told Oprah Winfrey. "Just trying to keep going."
Winfrey recently descended on the Atlanta home of Houston's sister-in-law and manager, Patricia (Pat) Houston, to talk with Bobbi Kristina and more of Houston's closest family members.
Poised and professional beyond her 19 years, Bobbi Kristina talked about how her mother continues to have a presence in her life.
"I can hear her voice and her spirit talking to me telling me, keep moving, baby. I can always feel her with me," she said. "She humbles me. I remember what she told me, I remember what she taught me. ... She was a sister, a comforter. The spirit that she had -- no matter where she was ... she touched everyone."
She revealed fairly extensive plans to follow in her mother's footsteps.
"We are going to do the singing thing, the acting thing, the dancing thing. It's a lot of pressure, but she prepared me for it," she said.
- Whitney Houston