Dyeing green hair to black without fading back to green?

Hi guys!!

I used to have blue hair and I have to dye it to a natural color for work, so I decided on black as it would be the easiest. My hair has faded to an olive green color and I was wondering how do I go about dyeing it without it eventually fading back to green?

I was thinking using a semi permanent red as a filler color then going in with a permanent black. I plan on using L’Oréal hi color black onyx as I’ve seen a lot of good reviews about it. Would this work? Does the red also need to be permanent or is semi okay? I don’t want to damage my hair too much, and Im also on a time crunch so I don’t have time to permanently dye it red then wait a while and give my hair a break before then dyeing it black.

I honestly don’t mind if it fades to brown as long as it’s not back to green!! Experiencing my blue hair fading to green after every wash has given me ptsd lol