How is Dark Messiah connected to Heroes of Might and Magic?

Agrail was obeyed only because of his talent and fear of Beleth; essentially, Agrail simply earned himself a reputation when they were choosing the Warlord's right hand, and he did so, it must be said, not without the help of Biara. As for Ksana's devoted love, she was simply trying to sway Sareth to her side and could not possibly love him if he freed his father, because she understood that she would be doomed to torment in Shio, and their characters are indeed very similar, at least in terms of cynicism, and Biara is not necessarily harsher than Ksana, just more loyal to the Warlord, and that's all. I've already talked about the appearance; Kha-Beleth looks strikingly different from himself in Heroes of Might and Magic V, with a different helmet, armor, no cloak or sword, darker colors, all of this, even with the adjustment for the cartoonish style of Heroes of Might and Magic V, are quite significant differences in appearance.