Sacha is the father of long-serving character Chrissie Williams's infant son, Daniel, as a result of a one-night stand, and has since held unreciprocated feelings for her.

Sacha tries to help fellow doctor Luc Hemmingway (Joseph Millson), who is having problems and invites him for a turbulent Christmas dinner.

When he learns that Daniel is a bone marrow match and is potentially the only one that can save Rachel's life, he authorizes the procedure without Chrissie's permission, creating problems between them.

After appearing briefly as Chrissie's one-night stand, Bob Barrett became a main cast member playing Locum General surgical registrar Sacha Levy at Holby City Hospital.

[5] He told Daniel Kilkelly of Digital Spy that he wanted to remain a part of the cast as long as his character had "a journey".

[6] In April 2017, episodes featured Sacha behaving out of character and Essie Harrison (Kaye Wragg) worries about his mental health.

This puts Sacha in a bad mood and he tells hospital porter Jason Haynes (Jules Robertson) that being a parent will eventually make him feel pointless.

[6] Michelle Lipton wrote the episode which aims to raise awareness of male mental health and the way it affects men who chose to ignore symptoms so they are not perceived as weak.

[6] The show's executive producer Simon Harper said that the episode was "incredibly important" and focused on "one troubled year in the life of one beloved, vulnerable character.

[6] Holby City worked alongside the British mental health charity Mind, their advice service helped the show create a really dramatic depiction of male depression.

Barrett told Laura-Jayne Tyler from Inside Soap that his character was dealing with depression the best he could but finds it tough at different times.

[11] Sacha takes a prominent role in the crossover when he is involved in a car accident with Beka, resulting in characters from Casualty having to save them.

[12] Barrett explained that although Beka receives the immediate help, Sacha actually has a more severe injury; he later collapses and requires surgery.

[12] Barrett filmed with Casualty at the Roath Lock Studios in Cardiff for two weeks and enjoyed being involved in a big stunt, since they were infrequently seen on Holby City.

[15] In October 2022, actor Jason Durr, who portrays David Hide in Casualty, posted an image of him and Barrett to his social media.

[20] A Daily Mirror critic jested "Bumbling doctor Sacha has never been lucky in love himself, so it's no surprise that he thinks the worst when he sees Essie becoming friendly with a colleague.

She opined that "Bob Barrett is a naturally smiley actor, but I loved how for most of the episode he somehow managed to keep the customary twinkle out of his eyes – we could see that Sacha was putting on a brave face and wasn't really happy.