Vanny's interactions with Jack and Dave
If i wrote an interaction between them (before you ask: no, i do not ship her with either of them) i'd have her act as a "younger sibling that you're forced to bring along with you" type character.
'Nessa would probably join one of Dave's schemes cause "sounds fun, why not" (he didn't even approach her or something, she just decided on her own to become a part of it).
Jack is fed up/tired of these 2 the whole way through but he keeps it to himself and endures their mischiefs; Meanwhile, Aubergine Man is initially against bringing her along ("it would be gay to have a woman on the team", as Doggy Daddy himself put as Ourply man justification). 10 minutes latter he goes "nvm i take it back" since he quickly gets overly attached to people who are friendly towards him.
Even before Henry he was likes this: it stems from the fact that he was uncared and unloved during his entire childhood and most of his teen years, only having TWO (now three) people in his life that moderately berated him; OF COURSE he'd cling to any sort of positive interaction he had with them.
Obviously, he won't be desperately clingy towards Van like he is with Jack or Henry, it would be someone he somewhat cares about but not by much, a middle ground between the two extremes of Eggplant Man's interactions: He either unconditionally cares about someone or couldn't give a shit if they died, and this would be an unique exception:
Between "All of this is for you, I will stalk you for as long as i can walk on this planet" and "Peter can go fuck himself" there's "Yeah she's cool she fly-kicked the plastic gremlin as a distraction while i lured the kids, awesome".
So basically she partially distracts him from how lonely he truly is, and he appreciates that, but it's FAR from enough, he NEEDS Jack and Henry's to feel complete company.
Davey's care-o-meter: Henry>>>Jack>>>>>>>>>>Vanny>>>anyone else>>>>>>>>>Matt
If he sides with them (that's the general assumption) i like to think he'd have to basically babysit her so that she doesn't turn Chica into a shrapnel bomb or something (plus the idea of a zombie having to babysit a grown ass woman on her 20s is hilarious).
He does not want to do this AT ALL but he'd do it for her own safety, for Toy Freddy's shins sake.
I could see him snapping and lashing out on her if she pisses him off enough, maybe beating her up depending on route (Legacy 100% bitchslaps her here, Neutral would have a misogynistic meltdown and get cancelled) but the more reasonable Jacks would at most just yell/cuss at her.
Y'all ever watched a movie with the "tired babysitter" trope? Yeah, it would be them, except the demonic child is on enough crack to kill 3 (fast)bears.
In a way, he's kinda being forced into a older brother role again so you could draw parallels to his relationship with Dee aswell as evidencing how he was affected by her death, making it pretty clear how devastated and broken he is now. He just can't do it anymore. He can't care anymore.
Everything Goes to Shit Part 2: Everything goes to shit even faster Staring Jack Kennedy feat. Vanessa (Directed by Bono)
Anyways that was a lot so uhhhhhh- bye?