[2] He was introduced in the season 6 episode "Invasion" as a surgical resident formerly from Mercy West Medical Center, following its merger with Seattle Grace Hospital.

[3] Jackson's main storyline involves his efforts to achieve success on his own merit, rather than relying on the legacy of his renowned surgeon grandfather.

Jackson had a series of romantic relationships with several characters, including Lexie Grey (Chyler Leigh), April Kepner (Sarah Drew), Stephanie Edwards (Jerrika Hinton), Maggie Pierce (Kelly McCreary), Victoria Hughes, Jo Wilson (Camilla Luddington), and April Kepner (again).

Jackson married Kepner and had two children: a son, Samuel, who tragically died of osteogenesis imperfecta type II, and a daughter named Harriet.

The younger Avery grew up hearing at his grandmother's dinner table about the nobility of being a surgeon, which inspired him to pursue that career.

Alongside April Kepner (Sarah Drew), Reed Adamson (Nora Zehetner), and Charles Percy (Robert Baker), he joins the staff at Seattle Grace Mercy West after the institutions are merged.

For comfort, he and Kepner both take rooms in the large house of fellow resident Meredith Grey (Ellen Pompeo).

Also living there are her husband, Derek Shepherd (Patrick Dempsey), resident Alex Karev (Justin Chambers) and intern Lexie Grey (Chyler Leigh), her half-sister.

For some time, Avery suffers because of the death of his friend Percy in the shooting, and having assisted in surgery on Shepherd while being threatened at gunpoint by the shooter.

The seventh season shows Avery's emerging interest in Meredith's sister, Lexie Grey, and they start a relationship.

Avery also starts working with chief of plastic surgery Mark Sloan (Eric Dane), who had previously had a relationship with Lexie.

In the Season 8 finale, Avery reveals to April that he is taking the position at Tulane Medical Center, despite feeling sick for leaving Seattle Grace Mercy West and her behind.

As a celebration of the conclusion of their residencies, the former chief of surgery Richard Webber (James Pickens, Jr.) organizes his annual dinner for them.

As a means to avoid each other, the two doctors decide to each bring a date to Dr. Miranda Bailey's (Chandra Wilson) wedding, both of whom are interns.

Jackson and April soon hit a rough patch when they realize that they have different views about the way their children should be raised with respect to religion.

They schedule an induction for the next day, and at the beginning of the appointment, they are asked to sign their baby's death certificate, which is too hard for the couple to bear.

In the Season 11 finale, Kepner tells Avery that she is leaving with Owen Hunt (Kevin McKidd) to serve as a trauma surgeon in the Army; it will help her grieve for their son.

In February 2009, Michael Ausiello hinted at the possibility of central character Meredith Grey (Ellen Pompeo) having another sibling.

Matt Webb Mitovich noted Williams's absence from the Seattle Grace: On Call webseries as a sign of bigger plans for the character.

[8] Shonda Rhimes hinted at the possibility of Williams and his co-star Sarah Drew, who portrays April Kepner, becoming series regulars in her blog post about the season finale in May 2010.

[13] Yang and Avery compete for the same cases, and in the episode "Invest in Love", Jackson witnesses Cristina taking charge of a situation for the first time, and he admires her, seeing her differently.

Speaking about Jackson's past relationship with Lexie Grey (Chyler Leigh), Williams said: "He tried to be safe and wise, avoiding romantic entanglements when he first transitioned into Seattle Grace from Mercy West.

"[15] Williams added, "They are both kind of suckers for love [...] they both get caught up in their own momentum [...] Avery’s all about his job and pressure from his grandfather, but he gets bowled over by this platonic relationship and can’t help himself with Lexie.

What they had was really unique and organic in the world of Grey’s Anatomy – two genders in a completely platonic, wholesome, pleasant, and productive friendship.

Struggling with grief, April seeks solace by joining the army and goes on tour with Owen, leaving Jackson at Grey-Sloan Memorial.

After several extended leaves, Jackson gives April an ultimatum, stating that if she doesn’t return to Seattle immediately, their relationship will end.

Jackson then has a brief relationship with Victoria Hughes (from Station 19) and a "friends with benefits" arrangement with Jo Wilson (Camilla Luddington) during the COVID-19 lockdown.

When Jackson leaves Boston (and the show) at the end of Season 17, he is unattached but departs with his ex-wife, April, and their daughter, Harriet, suggesting a potential reunion.

At the end of the episode, the couple shares an embrace and a kiss in the elevator, indicating that they have rekindled their romance while living in Boston.