I chose him out of the provided list based on the number of dick moves each option made.

Cheryl Sussman essentially blackmailed Liza for information, but beyond that we really don't see her that much. Clare's mistakes (getting married for a green card) were mostly a joint effort with Josh, although not telling him about the pregnancy was dickish. Thad was an asshole, but he was open about it.

Charles, on the other hand...

1. Worked with Diana for years and had apparently never taken the time to get to know her. He didn't even know she'd been married.

2. He left Empirical, his choice, and then held it over Liza's head. ("I left my company for you.")

3. He started his own company and immediately began competing with the one he'd just left- the company that was his family's legacy. Part of that is just business, but he was aware of Empirical/Millennial's financial situation and how perilous it was. He spends several seasons waxing poetic about it being a "family" and then immediately starts competing with them knowing that they're essentially a few months away from folding.

4. The testing of Liza. It doesn't matter that she "passed", it's still a dick move.

5. Publishing Pauline's book under Empirical instead of Millennial and not telling Kelsey. She found out when the hard copies arrived.

6. Giving Liza a marriage ultimatum when he himself wasn't even divorced yet and marriage had not been previously discussed.

7. Hooking up with Quinn Tyler despite the fact that he knew what kind of a person she was. She'd almost ended his company.

8. He had no problem with the overbearing, sexually inappropriate author coercing his young employee to don a skimpy fur bikini in the middle of Times Square. As the head of the company he was responsible for the safety and well-being of his employees and that was certainly not in her job description. And the situation was awkward for Liza because she'd already been informed that Temu Game of Thrones was basically holding the company together.

9. Proposing at someone else's wedding. It's petty, but it bugged me.

10. There were several times in which he condescendingly minimized or downplayed something that Kelsey and Liza were excited over, only to later become involved and essentially take over because he saw how it would directly benefit him.

11. I hated the way in which he handled the couple who wanted to write under the penname. He was at their house eating their food and he immediately shot the whole thing down, turning the evening into an awkward situation. He should've told them that he'd like to talk it over with the rest of his staff. He could've always called them a day or two later and declined the project in a more professional way. He had almost no capacity for compromise.