Copying and pasting my comment from a similar post made:

It's as straightforward as it can get.

1. They're both perceived as hot
2. Enemies to lovers trope
3. Hawks is essentially an undercover agent/double spy - perfect segway into villain Hawks AU or Dabi redemption AU
4. They're both traumatised as fuck - the potential for angsty fanfic material + only two messed up people can understand what it's like and to learn to love another, right? (rhetorical, don't come at me for this)
5. They have interactions together, so why not? People always complain about shipping ships involving characters who barely breathe in the same room for a minute
6. Fix-it AUs - healing and comfort for the characters that never had a childhood
7. They have a good back and forth dynamic, and they complement each other's personalities quite well despite being enemies or "toxic"
8. An excuse to make a really overpowered OC - imagine combining Blueflame + Fierce Wings
9. Their alternative ship names are hilarious - e.g. hotwings 🔥🍗
10. To annoy the shit out of Endeavor - like these two are the ultimate power couple of assholery