Yes, I get so tl;dr that these all get their own posts. :||| To be fair, Haru's feelings about Mammon are kind of complex.
She really likes Mammon quite a bit, in a platonic way. Since she came to Micro, Mammon's one of the people from home she got attached to quickly, both because of her situation making her feel lonely and Mammon making no real attempts to chase her off. And because of that, Mammon has become what Haru considers one of her closest friends, and she'll cling to that friendship tightly unless something pretty disastrous happens. Especially since Mammon is one of those people who doesn't seem to mind her bizarre behavior and has come to figure out when Haru's being genuinely weird and when she's trying to hide her true feelings and so on. :|b
Haru's come to know, or at the very least suspect, that Mammon really is female since Bel first mentioned the possibility. But she's also well aware that Mammon is androgynous on purpose, and that staying that way is important to hir. So Haru makes a notable effort to keep that intact; she treats Mammon a little differently depending on who they're with at the time. When they're in public/with people who Haru is unsure about in regards to knowing what gender Mammon is, she treats hir like a close guy friend. Including referring to hir as "him." She drapes on him, kisses his cheek when she's especially thankful or excited, says obnoxious things about how handsome he is or how he's going to make her swoon, etc. Just like she would any of her other close male friends. When in private, or with people Haru is absolutely certain know sie is female, she will treat hir as a close female friend instead. Drapes and cheek-kisses are replaced with quick snuggles and the like. She will talk to her about stuff she would never speak of to a man, will tease her lightly about men, would feel comfortable changing clothes in front of her, etc. In some ways that means she treats hir very differently in one situation than she does another. As a sidenote, since most of the locals are little more than drones, Haru is less careful if she's sure ONLY drones are around.
Even though she knows that Mammon is disdainful of most feminine traits or doesn't care for "girlish hobbies" or is touchy about that sort of thing in general, she makes a point to invite hir to do lady things with Chrome and herself. It's not that she expects Mammon to say yes if she asks enough, or that she wants to convert hir to the ways of women or anything odd like that (though she may use these as excuses in some situations.) It's just that Mammon is her friend, and there's the off-chance that it might be something sie does like, and even if it's something sie doesn't it always feels nice to be invited to something. So while she may invite her to do these things often, they never come with expectations and Haru is never really bothered when Mammon says no.
Since Haru isn't sure how much of the Arcobaleno stuff is a secret, and it's not her business anyway, she still maintains the polite fiction that Mammon is an adorable little baby saving up for college. This means she will still say ridiculous things like that in public, though she doesn't in private. Now that she's aware the baby thing kinda bothers Mammon on some level, she's careful not to mention it much at all when it's just them.
In reality, Haru thinks Mammon is a very vulnerable and perhaps shy or cowardly person. Sie goes to great lengths to hide hir appearance, to stay distant from people and not admit to hir own affection for anyone, and sie charges ridiculous amounts of money as a way to deter people. She believes that under all of this cranky old lady shell, Mammon is genuinely fond of hir friends in hir own special way. Sie can't ever admit it because that would be putting hirself out of that protective shell, but Haru doesn't think sie needs to. She never takes hir disagreeable disposition personally; in her mind, Mammon is just like Gokudera and Bel and Accelerator and only knows how to show fondness by being a grumpy granny. :| Also she thinks several of hir bad personality traits really did come from spending too much time with those unruly boys in the Varia. And if there's one thing Haru's getting used to? It's the Varia way of showing how you care.
Because of all of that, Haru also strongly admires Mammon in some ways. Sie can hold hir own in such a dangerous position, is self-reliant, determined, and calm in almost any situation. No one would ever dare to try and coddle or keep secrets from hir "for hir own protection." No one would dare to call hir useless. These are things Haru wishes she had, so these are things she strongly admires Mammon for relentlessly earning. In that way Mammon has started to fill the role model hole that's been empty since Haru's been in Micro, away from Bianchi. Because of that she's not afraid to cry in front of hir or come to hir for comfort or advice. And in hir own way, Mammon is very comforting. Sie is frank, and Haru can trust hir to say things like they are most of the time, to not coddle her and tell her "it will all be fine" while keeping her in the dark. Haru is especially grateful that she was included when Mammon updated everyone on what happened at home. Sie didn't leave her out on account of her not being useful or to protect her or any of those other things Haru is tired of hearing, and she really, truly appreciated that.
As for charging for stuff left and right, Haru never takes that personally either. She's come to liken Mammon's need for money to other women's need for comfort food. Mammon seems to honestly, truly need the profit to justify whatever hobby sie's doing to hirself. Like if it's profitable, it's okay. Haru relates this to her diet; if she won't gain too much, it's okay, if it's this, it's okay, etc etc. It also seems to be hir security blanket in that hir prices get absurd if it's really not something sie is okay with doing. To some degree, this odd quirk is useful! Haru can use how much Mammon charges to do any particular thing with her as an indicator for how much sie enjoys that thing. :'|
She figured out pretty early on that Mammon's got a sweet tooth too, and isn't above using sweets to bribe hir into stuff. On the other hand she just enjoys making treats for hir and sometimes will for no reason at all. She trusts Mammon a lot in most ways, like with her feelings and secrets (they aren't profitable to sell, after all. XD), and all that kind of thing. Haru KNOWS BETTER than to trust hir not to screw her over in the money department, but that's just another odd quirk of hirs that Haru won't take personally. Sie would cheat anyone, so it's hardly an indicator of how friendly they are with each other. And likewise, she suspects that she gets away with stuff Mammon wouldn't let just anyone else get away with.
IN SHORT MAMMON IS A+++++++ FOREVER EVEN THOUGH SIE IS A GREEDY MEANIEFACE. :')