The Scorned Elves pretty much hate everyone, yet they retain a begrudging admiration for orcs because of the Green Emperor. I mean, they don’t view them as equals but as creatures, perfected in their brutality, as something above the other races of Behatland.
Dwarves despise orcs. The grudge is deep, predating the Green Emperor. However, the Green Emperor is hailed as the worthiest of foes. None would ever question his might as a leader or warrior. Though dwarves may spit whenever someone mentions an orc, few would when they hear talk of the Green Emperor. It honours their ancestors that they died fighting such a great orc, an orc who conquered an entire continent. Better than being killed by an elf arrow!
The forest elves, long-lived and ever patient, rarely speak of the Green Empire. They, collectively, view the orc domination of their continent as a mere aberration of history. Despite sages uncovering lost lore suggesting a deeper kinship, orcs represent only the ruin of the world to most elves… Although elves have a bit of a superiority complex, even though they are in perpetual decline.
To the halflings, many claim to have simply ‘forgotten.’ Regardless of what the Green Emperor did, later emperors still ate them. The Green Empire remains a thing of terror, a fireside story to scare children. They go about their business and pretend events of ‘those years’ were just a big misunderstanding and best not talked about.
To humans, they have a more nuanced view. Their own history is that of a long empire. They view him as a historical figure, worthy of record. Opinions vary. Some regiments idolise him and pray to be given his prowess in battle. Others call him a tyrant. Some say he swept away an old, corrupted order which, eventually, allowed everyone to progress.
Goblins and orcs had a falling out in the later decades of the Green Empire. Yet, they love the Green Emperor as they remember it as a time when they could swagger around and pick on anyone they wanted, as long as an orc was close by. Of course, goblins will recount that it was their help which made him so great. Of course.
This is a generalised view. There are many exceptions since the Green Emperor is ancient history now.
EDIT: I use the contrivances of orc illiteracy to fudge historical memory and recollection. Not everything has been recorded. Much will be incorrect. I want to allow players to ‘squeeze’ their own Green Emperor into the mould, and canon is not firm. Except for the Scorned Elves. Here, I have made it canon that our Green Emperor saved and befriended Merchadi. He gifted the Scorned Elves a homeland, and Merchadi died by his side in the final battle.