a shark apologist in several fandoms

Origin, Timeline, and Age

Celine was a member of the idol/hunter group the Sunlight Sisters circa the 1990s with Rumi's mom (Mi-yeong, name taken from the gravestone) and Thirdlight (name unknown). We know it's the 90s from in-film and out-of-film details. In film, there's the one shot of the SLS's stage outfits that are incredibly 90s coded. Out-of-film, Maggie Kang, the director, puts Rumi's age at 23/24 in this Reddit AMA; assuming the film takes place in 2025ish there's a hard ceiling on the SLS's tenure of 2002, at the latest. In addition, SLS may have been inspired by the group S.E.S, but I don't have any sources on hand to verify that.

With this timeline, we can give a very rough estimate for Celine's age range. Assuming all the members of SLS are roughly the same age and Mi-yeong gave birth to Rumi in her 20s, Celine would be in her mid to late 40s during the events of the film. But, again, that's a very rough estimate. Someone who knows Korean family law better than me could put a hard floor on the age range if they know the minimum age someone has to be to become a guardian of a child.

On Being a Parent and Her Relationship with Rumi('s Patterns)

Celine raised Rumi, despite Rumi being half-demon. If the fans in the opening are correct, Celine has raised Rumi since infancy. There's a distinct lack of other adults in Rumi's life (no thirdlight, no Mi-yeong relatives, no Celine relatives) in both the film and other sources such as concept art, so Celine was likely parenting solo.

There's only one scene with kid Rumi and Celine in the film. In that scene Rumi calls Celine by her name--this continues into Rumi's adulthood and BOY does that detail drive so much fanfic, especially since the why of it is left to the imagination. And while Celine has a lot of conflicting feelings on Rumi being half-demon (more on that later) she is a capable of a certain amount of physical affection. In fact, physical touch doesn't seem to be a problem for Celine as long as she isn't actively looking at Rumi's patterns. While we don't get any on screen hugs, Celine is shown touching Rumi's shoulders in the kid flashback, in some red carpet photos, and in the tree confrontation scene. For the tree confrontation scene, Celine's hands go right on some of Rumi's exposed patterns before they get covered, but Celine has trouble with a comforting hand on the face because that's where she's looking at the moment (also, potentially a gesture Celine has done before with Rumi before?).

I know touch starved Rumi is fun for fanfic, but I don't think it's substantiated by canon due to what I described above. At least Celine being the originator of Rumi's hairstyle is canon, due to Celine braiding kid Rumi's hair in the flashback.

Circling back to Celine's feelings on Rumi being half-demon, signs point to Celine being in catastrophic levels of denial.

During the flashback with kid Rumi she:

Tells Rumi rather sharply to hide her patterns, but the only other person in the vicinity is Celine. Thus, the action is for Celine's benefit. Easier to be in denial about something you can't see.

Insists to Rumi that despite having patterns and a demon dad, Rumi herself isn't a demon. Rumi is a hunter and that's different. The paradox is already clear to the audience who have seen Huntrix (including Rumi!!!) use the patterns = demon logic in the lead up to the How It's Done fight.

With absolutely no evidence presented to the audience, Celine claims the Golden Honmoon will erase Rumi's patterns. How convenient that the Golden Honmoon can get rid of the only proof of Rumi's demonic heritage and that Celine knows this despite that the Golden Honmoon has never been achieved before, and Rumi's existence as half-demon is, to our knowledge, unique.

The confrontation at the tree further adds to the "Celine is in catastrophic levels of denial over Rumi being half-demon" fuel because during that scene Celine

Refuses to kill Rumi who is, at this point, visibly has demonic features and has a voice that seems to actively harm the last remnants of the Honmoon

Insists they can totally fix this despite, again, Rumi's visibly demonic features and voice that actively harms the Honmoon.

Has trouble touching Rumi's patterns when they're in line of sight and then has trouble looking at Rumi when all of her patterns are visible, to the point of closing her eyes.

When Rumi teleports out of the scene with her declaration that she's glad to see the Honmoon destroyed, Celine collapses to her knees. To me? That's someone who's been deep in denial who finally has been yanked out of it but can't do anything about it.

I think Celine's denial stance also explains why she took the "don't tell Mira and Zoey" stance, but more on that later.

This gets into analysis territory, but I do think Celine loved Rumi to the best of her ability and never intended to make Rumi so ashamed about being half-demon. But while Celine lived in denial for years, Rumi saw the incongruities in Celine's "you're not a demon, you're just a hunter with patterns and the patterns can be erased" stance, and those incongruities were fertile ground for shame.

Training Huntrix and Celine's Relationship with Mira and Zoey

Celine trained Huntrix to be the next generation of hunters. Outside of the opening, we have little knowledge of what this training entails or how long it lasted. Also, even though Celine knew Rumi would be a hunter at a very young age (see: the kid Rumi flashback) it's left up to the imagination if Rumi also began training at that young age.

We do know that during said training Celine said her infamous "faults and fears" line, and said it repeatedly enough for Mira and Zoey to make a joke out of it.

During the scene when Huntrix are going over Rumi's voice troubles, Zoey first suggests calling Celine before Mira and Zoey do their Celine impression joke. And then after the joke they agree that hiding and trying to fix Rumi's voice troubles is the course of action they should take. Notably, Celine doesn't get called. There's no evidence Celine gets informed about anything that happens during the film or gets involved in any capacity, only appearing in flashbacks until the tree confrontation.

I don't think Huntrix as a group has a close relationship with Celine, and Celine, after a bit, allowed Huntrix to operate largely independently. There's one flashback where Celine is in a location that might be Huntrix tower, might be an office, early in the Huntrix's career (based on Rumi's pattern progression) which is one of the few non-red carpet photo interactions between Celine and post debut Huntrix.

Back to the pre-debut: we know there's an initiation ceremony of sorts which results in the opening monologue by Celine. Of note is that monologue focuses on the Hunters as protectors of humans and builders of the Honmoon, with very little in the way of demon slaying. Whether this is deliberate on Celine's part is impossible to tell with the information we currently have.

We also have Celine's teachings filtered through Huntrix, which includes all the slaying and demon hating. Celine has the tiniest wiggle room of plausible deniability here, since we don't hear her teachings directly, but it's not much!

Lastly: Celine deliberately made the choice to withhold information from Mira and Zoey about Rumi. There's an argument that this is fear driven (she doesn't want Mira and Zoey to murder Rumi), but I think it's denial driven. Both Mira and Zoey strike me as people who would've seen through the bullshit immediately and pushed back on it. There's also an element that Mira and Zoey might have been worse at being hunters if they saw the humanity in demons.

(With Celine being absent from Huntrix's lives post-debut, there's an argument to be made that Rumi really should have told Mira and Zoey herself before shit when sideways but that's another post.)

Other Fun Details

Celine is starting to go a bit gray. It's hard to pinpoint when exactly she started going gray and the progression, but she doesn't have gray hair in the kid Rumi flashback and she does have some gray in the opening with pre-debut Huntrix. And then I think conservation of production resources kicked in because Celine's gray hair stays exactly the same for the rest of the film. Training Huntrix caused Celine to go gray confirmed?

@starrdio already made a post about Celine's fashion and you should read it. Here's a link.

Celine doesn't use a Honmoon weapon during the events of the film (and it's unclear how much access she has to hunter abilities), but her chibi cameo during the end credits dual wields twin swords (Ssanggeom?)

Things That Are Fanon

Celine was in love with Mi-yeong. Do I love this idea? Yes. Is is substantiated by the text in any way? Well...Celine probably has SOME feelings about Mi-yeong because she raised Rumi and goes on about "protecting what was left of [Mi-yeong's legacy]" but the specifics are left to the imagination.