Alright, so, I'm just gonna go on a couple theory rants about two of the rivalries we've seen so far. Those being Toffee vs Doom and Syndrome vs Doof. Sorry if this ends up kinda long.
To start off, let's look at why Doom hates Toffee so much. Now, it could just be normal things, like Doom being a generally hateful person or thinking that Toffee is a Toon or something, but my theory is that there's something more to it than that.
Specifically, it is my theory that Toffee is intentionally fanning the flames of Doom's grudge for him. And so, in true Doofenshmirtz fashion, I'm going to try and prove this by looking at Toffee's Backstory, Nemesis, and Scheme.
Backstory: Alright, let's just do a quick inventory of who Doom is and what reason Toffee would have for disliking him. Judge Doom was an outsider, someone who coveted the land that the Toons had called their own. To take this land, Doom gained a powerful weapon tailor-made to oppress Toons, rewriting history to make them look like the bad guys. Doom has forced the Toons off of the land they used to own, turning them into second-class citizens. Changing a few names, it almost seems like a mirror to the Monster's own suffering at the hands of the Mewmans. Now, I know what you're thinking. Toffee's a rational guy, he's able to set aside his own personal feelings to accomplish his goals. Doom seemingly reenacting the oppression his own people went through would be annoying, but not something to start a rivalry over. That brings us to our second point.
Nemesis: Or rather, what enemies does Toffee have to deal with right now? Well, let's think about it. Toffee is one of the few Kings, to be actively engaged in open warfare right now. Oh, it doesn't look like it from what we can currently see of his territory, but you've gotta remember that Toffee is currently fighting a war that spans across multiple dimensions, involving who knows how many other opponents. And Earth itself is even more precarious. We've seen that any step out of line, such as engaging in open warfare with another King, is generally going to be slapped down by every able-bodied faction within the US. Toffee really wouldn't want to set that off, so he's not coming in guns-blazing. But what if there was a way to make someone else step on that ridiculously explosive landmine? That's where part three comes in.
Scheme: It is my theory that Toffee has intentionally been provoking Judge Doom into engaging in overt action against another King, such that Toffee can come in and claim Doom's territory once he gets slapped down. Seriously, think about it. Doom is pretty much the perfect patsy for this sort of thing. For one, it's generally known that Doom has a short fuse and hates very easily. As an additional point, Doom can easily be regarded as the weakest of the Kings. His territory is the smallest, and the majority of Doom's weapons and minions are dedicated to fighting against one specific species. Plus, Doom just doesn't seem to have the numbers to actually hold any additional territory, given that he's just now making a robot army. Perfect for someone you'd want to be easily rebuffed. And for the hat trick, Doom is right next to Toffee, ensuring that Toffee would have an easy time of conquering Doom's former territory once he gets slapped down.
It's actually really important for Toffee that he be able to gain Doom's territory, and I'll detail why right here. It bears repeating that Toffee is one of the rare few Kings who's engaging in open fighting right now, and that he'd have a bad time of it if he just tried to take that approach on Earth. So if Toffee can't use his territory on Earth to engage in direct conquering, what does he use it for? Why, for feeding his ever expanding war machine so that he can defeat the opposition of other dimensions, of course! So Toffee definitely has cause to want more territory so that he can strengthen his armies, and what better way to do so than by taking Judge Doom's? Doom is small, disliked, comparatively weak, and possesses a potent economic force in Hollywood/LA.
But would Toffee actually do something like this? Well, yeah, absolutely. This is pretty much just what he does in the show: find some easily manipulated scapegoat to take the heat while Toffee sets things up from behind the scenes, and then set said scapegoat up to fail while Toffee takes their land and minions.
And while I'm speaking about Toffee, can I just say that he's an endgame threat on par with Bill Cipher? Like, seriously, think about it. We have absolutely no idea how many forces Toffee has available because he can trivially hide the full extent of his might in other dimensions. Toffee could spend literal years creating an army and weaponry sufficient to stomp every other King, and literally no one could find out about it because everything was done in an alternate dimension. While it's not quite as in-your-face as Bill "Literally a God" Cipher, Toffee still possesses a large advantage over pretty much every other King. He has access to way, way more territory than any one else, and the ultimate Anti-Intrigue tool in that he can hide all his secret projects in another dimension. We have literally no idea what Toffee is even doing at any given time, nor will we know if he's gathered up a force sufficient to conquer Earth until it's too late.
Anyway, that's all I got about Toffee. Let's talk Doof and Syndrome now.
So, we know that Syndrome dislikes Doof a fair bit, even if we don't really know why. I'm gonna try and list out a few theories/explanations for that.
1) Doof is pure Golden Age Maximum Ham, and Syndrome probably dislikes that.
2) Doof and Syndrome have opposite approaches to Evil Science. Syndrome takes one particular design/idea and then improves that over the course of years, while Doof pretty much just draws his ideas out of a hat. Additionally, Syndrome tends towards "hard" sci-fi, while Doof just casually breaks the laws of physics and goes full conceptual.
3) Doof is a weird joke and yet somehow is still matching Syndrome. Looking at the territory map, it looks like Doof and Syndrome both have around the same amount of territory. Syndrome has a huge corporation? So does Doofenshmirtz, even if Kronos might be way more successful than DEI. It could rankle Syndrome's pride a bit that a "joke villain" like Dr. D is still in the same league as him.
4) Heinz Doofenshmirtz has the life Buddy Pine always wanted. Disregarding backstory stuff from Drusselstein, Heinz is actually living a pretty good life for a supervillain. While Buddy is constantly locked up in his lair, scheming vengeance against Mr. Incredible, Heinz has managed to make genuine connections with others. Heinz has an amicably divorced wife, a loving daughter, a pack of groupies from L.O.V.E.M.U.F.F.I.N, and most importantly, an extremely great relationship with his nemesis, Perry the Platypus. And what does Buddy have? A spouse, any friends, literally any genuine connection with another living being? Nope, Buddy doesn't have jack.
Just think about it. Perry and Doof had bowling nights, went on to national tv for what was effectively couple's counseling, and even had a whole musical number about the bond that they shared. Imagine how much seething jealousy that ignited in the Mr. Incredible fanboy that was Buddy Pine. Just what he would give to have a relationship like that with Mr. Incredible, and this absolute joke gets to act like that with his own nemesis?
I dunno, just some thoughts I had about all this.
