Steve Mannheim is one of Hollyhock's adoptive fathers.
Not a whole lot is known about him individually but like all of Hollyhock's fathers, he doesn't like BoJack but understandably so.
He is just trying to protect and take care of Hollyhock along with the rest of the dads and he is definitely a loving father.
He seems to be one of the more tempered and aggressive fathers when it comes to keeping BoJack away from Hollyhock for her own safety.
Steve Mannheim is a human man who appears to be middle aged, judging from his curly grey hair. He has wrinkles on his forehead, bags under his eyes and stubble on his chin.
He wears a blue v neck t-shirt and brown pants with white suspenders and grey ankle length boots.
According to the model sheets, he is slightly above 6ft tall.
The eight men adopted Hollyhock, born September 24, 2000, and who was sired by Butterscotch Horseman and his maid/mistress Henrietta, sometime when she was still an infant.
They sometimes communicate with a Dad Speak of which the intent that people outside of the relationship (including Hollyhock) wouldn't be able to understand it.
However, unbeknownst to the dads, Hollyhock understands what they're saying perfectly well.
They live in Wichita, Kansas.
They are mentioned numerous times, throughout Season 4 by Hollyhock.
They make their first appearance in Lovin that cali lifestyle!!, when they travel to L.A. after Hollyhock accidentally overdosed on amphetamines, which unbeknownst to anyone at the time was due to Beatrice putting weight loss supplements in her coffee.
They blame BoJack and refuse to ever let him see her again.
In What Time Is It Right Now, BoJack travels to their home in Wichita, Kansas, and after begging them to hear him out, he explains how he discovered he isn’t actually Hollyhock’s biological father—his father Butterscotch is.
He also found out Hollyhock's mother is his family's former maid, Henrietta Platchkey, and he wanted to give Hollyhock her phone number.
They agree to tell her, but still tell BoJack to leave.
They seemed to have allowed Hollyhock and BoJack to talk again, as Hollyhock and BoJack continue to have a far distance sibling relationship afterwards, even visiting him in Ancient History.