system
Given the following post, respond as if you're commenting on Reddit:
human
[Halo] Why do grunts and jackals dislike each other.

I noticed in infinite grunts and jackals have a lot of dialogue shitting on each other.  This doesn't seem to be present with any of the other races, not even elites and brutes who would have obvious reasons not to get along.
gpt
It's a holdover from their historic animosity while part of the Covenant going back to when the Unggoy were forcibly inducted into the Covenant a few hundred years ago.

The Unggoy's high birth rate meant that, on High Charity, a lot of Kigyar had to be relocated. This constant moving put a lot of stress on their females, which caused infant mortality to spike quite high. Those that didn't move and tried to share space often found themselves crowded out anyway, their nests (inadvertantly) crushed by the constant swarms of Unggoy.

In response to this the Kigyar tried to poison the Unggoy's recreational drug supply which would have sterlised large numbers of them. The Covenant leadership found out about this and... did nothing. This caused the Unggoy to finally rebel in 2462. The Kigyar were only too happy to help put down that rebellion, which only ended when an Arbiter partially glassed the Unggoy homeworld.

And as one final twist, their surprise successes during the rebellion ended up proving the Unggoy's combat prowess to the Sangheili, who from then on allowed the Unggoy to be part of the actual armed forces of the Covenant instead of just unarmed cannon fodder. This further incensed the Kigyar and the two races have been at odds ever since.