It turns out Moon Knight almost had another MCU character in it, but they were removed in the end as the studio decided to go in a different direction.
EP Jeremy Slater has revealed that Hawkeye‘s Echo was supposed to be the main love interest. Though ultimately, Marvel felt that she just didn’t work well in the series.
“At the time, Echo was going to be our love interest, solely based on the fact that they knew Marvel liked the character of Echo and was trying to find a show to put her in,” he said. “[But] they were like, ‘You know what, we’ve got this Hawkeye show and we feel like she would fit in a lot better there…’”
Frankly, Echo is a much better fit for Clint Barton’s solo project than she is for Marc Spector’s and it’s certainly not like Moon Knight is suffering due to her absence.
Source: The Direct