Mor'du counts Pitch as an ally rather than a master or whatsoever. He fights with massive strength and is a great advantage for Pitch.
Mor'du doesn't pay much attention to Gothel, or one could could say that he doesn't pay attention to her at all. He only tends to get angry when she calls him nicknames during conversations with Pitch Black like : animal, hairball, black thing, fuzzy, etc.
Mor'du and the Red Death appear to be very similar. They are both animals, aggressive, and they have a rival that they had sworn to defeat. They like to have 'friendly fights', if one could call them 'friendly'. They tend to use those 'friendly fights' as training. During their 'training' they like to bite, claw or wrestle, but because of their thick skin/fur, they don't really hurt.
Mor'du and Drago don't necessarily get along because of Drago's history as a hunter. They will, on occasion, work together to achieve a common goal.
Merida is Mor'du's primary foe as it was she who defeated him in the film Brave. Though he lacks true human intelligence, he recognises Merida as an enemy and will stop at nothing to kill her and her friends.
Mor'du has little to do with Jack unless he stands between him and Merida. In such circumstances, he will attack with great ferocity. Being equipped with thick fur, Mor'du has a high resistance to Jack's main powers of ice and snow.Toothless (Hiccup's dragon) however is a different story. They are both powerful and strong which often leads to extremely violent confrontations, usually with Toothless coming out on top in order to protect Hiccup without the use of fire or flight. When he first saw Hiccup riding Toothless, Mor'du realized the true danger that Hiccup posed.
Mor'du pays absolutely no attention to Rapunzel, even when she stands in front of him; he simply beats her aside.
Toothless is one of the honorary members of the Four able to fight Mor'du on even terms. Not only is his skin as durable as the Demon Bear's, if not more so, since he is a dragon, but he can both fly (if Hiccup's on his back) and breathe fire, and the power of his plasma blasts could blow Mor'du onto his flank or kill him. Because of this, Mor'du and Toothless have a mutual hatred of each other.
Friends and AlliesEdit
If Mor'du was human during his interactions with Hans, they could share their own bitter frustrations at being passed over in favour of their siblings for the throne, although Mor'du's own brutal reputation would prevent him and Hans from ever being true friends, reminding the Southern Isles prince of his own abusive brothers. If Mor'du was a bear, in contrast, Hans would see him as little more than a tool or a weapon to be used against his enemies.
Being a large animal, the demon bear would be considered too slow to be an actual threat to anyone. Despite this, Mandrake could use him as a means to breach the barriers of Moonhaven, much like a human army would use an elephant.
King Candy would most likely use Mor'du as an enforcer/weapon against his enemies, manipulating his blind rage and destructive nature to kill anyone Candy considered a challenger to his rule. He would not enjoy his services, however, and seek to get rid of him as soon as he is no longer useful.
Yokai would sympathise with the human Mor'du's desire for revenge, although he has a far better cause in his own mind, since Mor'du sought revenge on his family, while Callaghan sought revenge for his family. The Demon Bear, in contrast, he would only see as a dangerous monster and a weapon.
As a human, Mor'du would remind Elsa of the Duke of Weselton's bodyguards who tried to kill her, and fear him. As the Demon Bear, she would fear him more. Due to her cryokinesis, she could actually fight back against him, freezing him in place or blowing snow into his eye to hold him back. Mor'du himself would mainly ignore Elsa unless he discovered her true power.
Mor'du would remind Anna of the wolves that attacked her on Kristoff's sleigh. Due to her plucky nature and being very hard to scare, Anna would defiantly fight back against the Demon Bear, although whether she could do any physical harm to him is debatable. Learning about his past as a human prince would remind her of Hans and turn her further against him.