Aren't you forgetting that from Vanessa's perspective, Bella approached her, trying to pull her into Bella's intrigue and use her? She realized that fast and played a brainless bimbo to find out more about what Bella's game and goal are and how exactly is she trying to use her. Why the hell should she be honest or even friendly towards people who are trying to use her?
You are calling it deceitful, I call it smart and totally fair move against deceitful and manipulative people.
Bella was the deceitful one there, don't forget that simply because you like Bella.
We don't really know what her goal is with the games with the Holgerssons. Maybe she is using Mario, maybe Mario wants to be used? I'm not judging before I have more information.
The way she tested Nika's reactions may also have something to do with the connection between Bella and Nika. Vanessa still doesn't know what Bella wants and why, so maybe she was trying to see how easy it would be to manipulate Nika and get that information from Nika instead of Bella.
She is smart and won't let Bella and Nika simply to use her for their Holgersson games. I like that about her.
And she has been fairly friendly (as of pre 4.5 beta that I haven't played) towards the people who tried to manipulate her.
I agree with almost everything you said. But she said that she sees most men as the weaker sex, not all of them. Whether she thinks that Nika is a bug in the system that needs to be fixed I have no idea. It's too early to judge, but we'll see.
As for insincerity, I only meant that she says what she really thinks. This does not mean that she in't manipulative and doesn't hide her real intentions.
I judge by what I have seen myself. We don't see Bella and Vanessa meeting. Bella might have formed a biased impression. If not, then it is obvious that Vanessa sensed something was wrong or already knew about Bella's intentions because there is no other explanation why she behaved differently with her. If she had been sincere with her, she would have shot herself in the foot. It's the same with Nika if he's on Bella's path. Besides, she was as sincere with him as possible in her situation. She openly let him know that she knew about his connection to Bella.
ps.
Saw the message of Patreon acquiring f95zone. Literally the best april fool's joke in my life lol.
Responding together as you both make the same point. I'm not a Bella fan. Bella being deceptive does not make Vanessa's deception any less deceptive. Vanessa could have been honest and still called Bella out, Vanessa could have just not engaged with Bella, there are so many options to not be deceptive. Vanessa leads Bella on because she love mind games. It's not about tit for tat, responding to fire with fire or anything. Ethics is an independant status that we should hold to regardless of anyone else's two-faced antics. All Vanessa's behaviour towards Bella shows is that she like to play deceitful, manipulative games, which is 100% her character throughout the game. At the point that Vanessa meets Bella, how does she know why? We know why, but Vanessa defaults to ...something because she thinks Bella's someone she can leverage, without even knowing (at that point) why Bella's approaching her. If she does know, is she storing the information for future blackmail/leverage? She is not being transparent or sincere in her first interaction with Bella, regardless of Bella's intentions.
Similarly, there is no ethical way to justify how she exploits Mario's affection for her own purposes. She is blueballing him into wearing a buttplug, doesn't matter that she justifies it to herslef by also wearing one. She is manipulating him into doing something he would unlikely choose for himself by withholding sex, implying that if he submits to her antics, he'll get a reward. She's grooming him for her own amusement, while looking down on him. Is that the basis for a healthy, loving relationship? Sure, hold off sex if you're inclinded to treat it as something special, but leveraging it like that, knowing he would be ashamed if it got out (while telling people she's just met, please let it get out she thinks) while dangling a carrot of a reward - she actually cheapens their relationship. Sex becomes transactional, and a reward for how much he endures. And the first moment she meets Nika, she's attempting to seduce him and cheat on weak, faithful Mario, further abusing him. So she dumps Mario to be sincere? Or does she continue being manipulative and deceitful?
Even throwing out the knowledge of Mario's buttplug is a double game. She can test Nika and Nami's integrity to find out what kind of people they are - if rumours spread about Mario, she knows from where. She's a pretty stand up girlfriend

Nika would be wise to notice how she treates Mario as being her default mode of behaviour.
The fact that she is friendly is another misdirection. She knows Noji is important to Nick, so she is the dutiful host. Don't forget that she knows about Bella and Nika, but says "I don't think we share the same social circles" when Nika says he thinks he's seen her before. More misdirection. She triggers Zara to be more competitive towards Nika, then actively bets (the driver's license) against her while knowing what their mom did to Zara, belittling her own sister for the sake of a stranger she's just met - playing games with her sister's mental health.
She applies social darwinism to ther ethics, and that ubermensch mentality is something I despise. Weak people shouldn't be exploited even if we don't like them - or should Vic be exploited like Mario too? Or Damian? How does Nika respond as someone with crippled emotions? He supports Damian to further his own goals (well, baskets), and he has many choices to be kind to Vic, and it seems cruel to me not to take the chance to be supportive.
On the social darwinism, her "I'll never need to work, I'll see where life takes me" attitude also shows she's really entitled, and she's into Mario as a gold digger. Zara still has goals, Vanessa plans to float through life amusing herself at other's expense. If she doesn't go for Mario, does she just sponge of daddy Nick? Her plan for her future is to manipulate people so she can be indolent in her lifestyle.
Nika also doesn't judge Vanessa by what Bella's seen, which is why he calls her to call off interacting with Vanessa, because he realises how manipulative Vanessa is. But I still love this to describe her:
Shit, they really got me this time)
I am literally am too old for that kind of gag, even if I was born yesterday apparently....