The Allfather demands it.
Atreus’ killing of Modi would go to serve as one of the major, if not, primarily catalyst for Atreus‘ growing arrogance.
Both Móði and Magni appear as antagonists in the 2018 video game God of War, voiced by Nolan North and Troy Baker respectively. Visibly distraught by the death of his older half-brother having taken place right in front of him (as well as given by the fact the two believed themselves to be incapable of dying), a horrified Modi backs away from Kratos in fear while struggling to speak in terror and anger.
Modi es el hijo menor de Thor que aparece como enemigo junto a su hermano Magni en God of War (2018).
" Magni: You. Magni was favored by Thor himself to the point where the mighty god would become furious at Modi after Magni's death, believing that he left him to die. Kratos, Magni's killer, fears no judgment but Mimir states it's their vengeance he should worry about. Modi introduces himself by jumping down from up above and blocking Atreus’ escape. With this result, Thor brutally beat and blamed Modi for letting Magni die, as well as brand Modi a coward. Magni orders the father and son to surrender but Kratos refuses to comply thereby starting a brawl between them and the sons of Thor. He is the grandson of Together in their youth, Magni and Modi — no taller than shrubs — managed to rescue their father after he had accidentally got himself trapped underneath the corpse of the Growing up, Magni would be regarded as Thor’s favourite son while Modi would be simply regarded as nothing more than Thor’s second son and Magni’s brother alone. Modi is largely a dishonorable sadist, as he takes enjoyment in tormenting Atreus about Faye and asks Magni if he can get "the kid" when they find him and Kratos. In addition, due to Thor’s favouritism of Magni, Modi was treated little more than a lesser son by his father, causing him to develop an inferiority complex from living in Magni’s shadow.
Both brothers are among the few to survive the apocalypse, and the two became the new owners of Mjölnir.
It's not entirely certain about Modi's intentions towards Atreus but it is likely that Modi prefers to fight those who are weaker or more vulnerable than himself, only participating in fights that guarantee his survival, unlike Magni who is confident in his abilities and likes a challenge. Magni is subsequently killed by the latter in a battle, with Modi fleeing. After being shot with several arrows by Atreus, Modi turns tail and runs away; disappearing over the side of the cliff and into the bellows of the canyon.
Only after his beloved, yet rival, brother is killed did he come to fear Kratos, and his cocky personality was soon tinged with cowardliness, immediately fleeing for his life after the shock of his brother's death.
Modi wears brown fur-edged leather shoes, blue-colored pants with knee protectors, and an armored loincloth with belly armor held by two brawn belts. Magni wears black leather pants and shoes, armored loincloth with added belly armor held by stick leather belt attached to a blue metal nuclease-like holder in the way of braces while most of his upper body is exposed.
As such, it is ironic that Modi's own name translates to "courage". This is also shown with Mimir, as Modi stays behind to taunt him while he was stuck in the tree. He was an Æsir god and the eldest son of Thor.
On his body are scars from battles and several tattoos of Norse runes which covers his chest and back and his face. As such, his rudeness and vulgarity could be seen as a result of this inferiority complex. Both follow under their uncle Baldur in attempting to find and kill the protagonist Kratos.
This is also seen as Kratos tells Atreus to go out from their fight, understanding his effort and worrying about his son but still let him to Modi.
As a result, Modi would think that everyone, particularly the Aesir, would see him as a joke, rather than as the worthy heir to Thor. When Kratos killed Magni, Modi believed that since his more favored brother was gone, he would only get the famed hammer by default, rather than proving himself worthy.
He also smelled Magni also appeared to demonstrate some twisted form of honor as he was willing to give Kratos and Atreus a chance to surrender without a fight but was perfectly (even preferably) willing to confront them when they refused.
He has two braids in his beard, by his chin, like Magni. Both brothers have the same father but different mothers, making them half-brothers. „ ~ Magni and Kratos.. Magni is the major antagonist in God of War. As a result, Modi strived to one day outdo his older brother and impress his father by proving himself worthy of inheriting Thor’s prized hammer Shortly afterwards, Magni and Modi split up from their uncle in order to hunt Kratos and Atreus. Magni: Ah... Good. As such, Modi is extremely insecure about proving himself the one to rightfully earn his father's hammer, specifically due to Thor's favouritism over Magni.
He also showed blatant disgust at his brother after Modi asked if he could keep Atreus to himself, suggesting that, unlike his brother and uncle, there were limits to how far he was willing to go in his depravity.
He and his younger half-brother Modi both follow their uncle Baldur in the quest to find and kill Kratos. Both brothers also had a reputation of apparently low intelligence, as they were constantly called idiots/fools by a number of characters, such as Baldur, Mimir, Kratos, Sindri, the latter who referred to them as "Thor's idiot sons" and Brok who called Magni a loudmouth.
Despite their childishness, together in battle, the duo were a formidable force.
Sadistically amused by the mere sight of Atreus, Modi takes advantage of the fight by proceeding to mercilessly mock Atreus constantly throughout the battle; taking immoral pleasure in insulting the young boy and trying to get a rise out of him. On his upper body, he wears stick fur which cowers his back to waist added to nuclease-like holder around his neck while his chest is exposed and covered in an Elder Futhark tattoo.
Kratos: No.
He looks much more like his father than Magni, having ice blue eyes, brown hair, and a beard that covers half of his face.