John Matze, fired last month as CEO of social media app Parler, tells Axios on HBO that he feels "betrayed" by investor Rebekah Mercer, the heiress daughter of hedge fund billionaire Robert Mercer.

Why it matters: Never before has a social media startup risen so high and fallen so far in such a short period of time.

• Matze says he first met Rebekah Mercer while doing IT consulting for her father's firm, and remained in touch.
• "She seemed very nice ... and I don't judge anybody by the press that I see."
• Mercer helped fund Parler in 2018, and she became its controlling shareholder. Matze says she and her people began getting more operationally involved as the site gained traction around the 2020 presidential election.

Early cracks in the partnership began to form last summer, according to Matze, when there was internal disagreement over how Parler should define "violence" in its terms of service. He claims that he wanted a broader definition than what was ultimately adopted, although he publicly supported the TOS in several subsequent interviews.

• But Matze, whose libertarian leanings seemed to interfere with his ability to be a strong CEO, says the internal conflicts intensified around Jan. 6, as Parler's popularity peaked and its problematic posts proliferated.
• In short, he says he wanted more automated moderation than did Mercer's reps and allies, adding that Parler had added a remedial AI solution just before being kicked off of Amazon's cloud hosting services.
• Matze claims he continued advocating for moderation, as a way to get Parler back online, but was met with resistance. It's a retelling that seems supported by recent public statements by Dan Bongino, the Trump acolyte and Parler shareholder who has criticized Matze for speaking publicly about his firing.
• Matze, who says he voted for Trump in 2016 but didn't vote at all in 2020, was fired via email on Jan. 29.

What he's saying: "I thought I knew her. She invited my family on trips with them and everything. I thought that she was, generally speaking, I thought she was being real. And then she just abruptly has her people fire me and doesn't even talk to me about it."

• "I feel like it was a stab in the back by somebody that I thought I knew. And so for me, you know, I would never do business with her again."

Go deeper: Ex-Parler CEO says he didn't want Trump deal