To quote myself:
"Speaking of Surge, in my head Scourge and Surge are perfect for each other in the most ironic of twists. It's only tangentially related, but after the RandomGoonVO vid of Scourge meeting Surge and doing the “You’d make a great couple,” I now headcanon that they legitimately are perfect for each other and they absolutely hate it. They’re so in sync and have even knocked boots but they’ll never admit to being more than just haters for each other--Because Scourge is everything Surge hates about Sonic, and Surge is everything Scourge hates about himself, which in effect makes them even more perfect for, and against, each other. Paradoxically."
You have to consider what they are personality wise. Arrogant, punkish self centered individuals who believe they have a right to lash out as they do due to their trauma (Scourge being abandoned emotionally and mentally by his father, who caused the Great Collapse and caused worldwide anarchy Anti-Sonic grew up in after he killed his own father, and Surge's abandonment, programming, experimentation, and mind overwrite by Starline) and their power (Sonic V Scourge on Moebius, Surge V Metal), hating the idea of being controlled (Scourge by the Multiverse, Finitevus, and others, Surge by Starline, Clutch, Eggman, etc.) who style themselves in punk and rebellion, whilst also being mirrors and critiques of Sonic's values. They are perfectly made for each other, because they together are everything they need for introspection, emotional nourishment, advancement as people, etc. At the same time, they are self-destructive, reject growth, and hurt those they love or care for. They would hate that they're perfect for each other, which makes them more perfect for each other. Furthermore, they exist as the things they despise to each other, and would drive them further towards and apart from one another. They're this paradoxical perfect pair.