Season 10 of NCIS: Los Angeles was relatively light on the Hetty action due to some real-life circumstances for actress Linda Hunt. She did have a presence in the second half of the season following the big wedding episode (and part of a key conversation with one of those JAG characters), and Season 11 will deliver something big on the Hetty front: an episode filling in some of her blanks.
Showrunner R. Scott Gemmill teased some of what to expect from the episode:
[It] focuses on some of Hetty’s backstory, so that’s fun.
So, fans who were bummed about the Hetty shortage is Season 10 could have quite a treat in store for Season 11! And that's not even the only good news about some of Hetty's backstory being explored. The episode isn't being penned by somebody who has barely contributed to the show over the years. TVLine reports that Eric Christian Olsen, who has played LAPD detective Marty Deeks since Season 2 and for well over 200 episodes so far, wrote the episode.
While Eric Christian Olsen isn't exactly a veteran writer of the franchise, he undoubtedly has the knowledge to fill in some blanks of Hetty's history without contradicting what the show has already revealed about her. Olsen isn't the first major cast member to step behind the camera on NCIS: Los Angeles. Chris O'Donnell, a.k.a. Callen, has directed several episodes over the years.
Hetty's big return in Season 10 actually came in what was a pivotal episode for Deeks, when he finally tied the knot with Kensi despite a whole lot nearly derailing the wedding. Linda Hunt was absent for much of the first chunk of the season while she recovered from a car accident.
R. Scott Gemmill revealed back when the wedding episode aired that Linda Hunt really wanted to be the officiant for Kensi and Deeks, and that "was a real incentive for her" to feel comfortable returning to the series. She didn't want to miss the wedding, so she "soldiered on" and came back.
I can't speak for everybody, but the wedding episode wouldn't have felt right for me without Hetty. Has she been detrimental to Kensi/Deeks from time to time? Sure. Still, she encouraged them at times when they needed it, and she really is the head of the NCIS: LA family. A withholding, mysterious, deadly head of the family, but the head all the same!
Although there's no confirmation at this point of when the episode will air, it has already been written, so I would bet on it airing in the first half of the season. The early episodes may focus on the cases that brought the JAG characters back into the fold, but with Barrett Foa's absence in the first chunk of Season 11, there may be the room for a character-centric story. I'd be surprised if there wasn't still room in the episode for a shootout and/or car chase, because what's NCIS: LA without shootouts and car chases?