So so interesting that Stolas had Octavia when he was 18/19 and it's never explicitly stated but it absolutely informs their entire relationship.
Like. He was barely older than Octavia is now!! She's (reasonably) an immature kid since she's 17 but Stolas was only a year older when he became a father. A year doesn't magically transform a person from a literal child to a whole adult. It's hard to hold Stolas' parenting to a particularly high standard when that's the start he had.
But let's deconstruct: Stolas has no idea how to parent. We never see his mum and his father is laughably emotionally neglectful & practically absent. Stolas goes from a teenager with zero friends or positive role models to a teenager with an abusive wife and an infant. And also still zero friends/role models. Yet, from what we see, it's clear Stolas follows some tenants of parenting in those early days:
He's very present! Likely to an overbearing degree. His father was never around so Stolas develops a co dependent relationship with Octavia. Stella isn't interested in caring for her (seen in the ep2 flashback & portraits) so Stolas does most of the parenting.
That said... He doesn't act like a parent in a lot of ways. He's protective & comforting & kind, absolutely, but Stolas doesn't have the emotional maturity to instill into Octavia. He's pretty much flying blind in that aspect, leading to her developing a lot of the same complexes he has despite (on the surface) a less lonely childhood. We see that very plainly in Sinsmas (excellently explained in 3BSkyen's video!!)
Anyway - this early stage of Octavia's life is pretty easy for Stolas in comparison to the rest. When she's a little kid, he essentially just has to be the fun, kind parent. Yes, he wakes up at night to comfort her, but he also probably has a fleet of nannies to support most of the time. He can take her to Loo Loo Land (and not notice that she's scared of RoboFizz) and promise to see Azathoth's tears with her (in a distant future that he can't keep track of), while discipline and child-rearing take a major backseat.
A lot of it is actually... Performative. Not that he doesn't genuinely care, but he expresses the care in performative ways (likely taken from his limited reference point - fiction - and his own, singular childhood trip to the circus).
But then we see his age also play a big factor. Even from the beginning, Stolas struggles to treat Octavia appropriately. He is her dad but he is also a teenager with almost nothing to compare himself to. He sings a lullaby about dying! To his tiny owl daughter!!
And when she gets older, this only becomes more difficult. Stolas was forced to grow up so prematurely that his teenage years likely weren't any true extension of childhood like Octavia's are. When she's five, Stolas recognises how to interact with her and maintain closeness because he was also five at one point. When she's 17 and (thankfully) not burdened with imminent marriage & parenthood, Stolas gets caught between two extremes:
1. Infantilisation (attributing interests to her from a decade ago, not trusting her with basic details of his life, "language!" when she swears, carrying her during ep2)
2. Treating her overly casually, like friend (describing his sex life in front of her in extreme detail, "people want our money and our bodies", calling Stella a bitch in front of her)
And obviously, this sucks for Octavia! She's at once not taken seriously and placed in an uncomfortable position beyond what she can handle. She's old enough to handle knowing that Stolas takes anti-depressants & that he and Stella haven't ever been in love - information she's denied - but not in a position where her dad should ever be talking about his affair partner's "big dick" in front of her.
But Stolas can't navigate this. He understands the latter is inappropriate but slips multiple times because he finds it difficult to conceptualise this version of Octavia. When pushed, he recognises that she's "too old" for certain things, but in the same breath he can't bring himself to speak openly with her nor treat her like a nearly-matured individual.
And they're so codependent that it's pretty impossible to form healthy boundaries. In Sinsmas, Octavia is right to say that Stolas shouldn't have "stayed miserable just for" her, but equally she resents that he tried to reach out to another person other than her for happiness. Of course, he did it in a very flawed way, but there's still elements of hypocrisy to what Octavia says. In the same vein, Stolas Hypocrite Goetia spends 17 years giving Octavia a "normal life" only to blow it up in the most disastrous fashion possible without a word of honest explanation.
Because they're both acting immature!!!
Octavia is literally a teenager and Stolas is basically in a state of arrested development. It comes through in his parenting but (more obviously) in his grand, soap opera worthy gestures to Blitzø at every narrative turn. He can't understand Octavia as a teenager because was never really treated like one, and so he defaults to treating her like a child or speaking to her like an adult. The same way a lot of teen parents can present more like older siblings.
And I can only imagine this is exacerbated by the Goetia life span being infinite. Imagine having a one thousand year life span and having a kid at 18!! For their species, that's a laughably short amount of lived experience.
It's interesting to compare Stolas & Octavia to Blitzø & Loona. Technically, their age gap is even smaller (about 14 years) but Blitzø took Loona in when he was in his thirties. There's none of that weird infant stage to get muddled in, and it's also more appropriate for Blitzø to be vulgar around her since Loona is more mature. He still infantilises her though - but that's more a product of Blitzø's own fifteen complexes.
All of this to say. Wow. Stolas & Octavia's relationship can't heal until Stolas does some personal growth (because his best intentions simply aren't enough anymore). However, Octavia needs to build up some empathy for her dad. They're so similar and Stolas has put Octavia in a much more secure, safe position than he had at her age. Not a perfect position, mind you, but he is also a mentally ill victim of domestic abuse... So let's all invest in some sympathy actually. If someone would just let Octavia in on that information, it would clarify a lot of their issues to her.