I don't know if you're familiar with the concept of yandere, but I can clearly see the greens and the blacks as yanderes for Jace.
Romantic Yanderes: Aemond, Aegon II, Baela, Daeron, Cregan and Lucerys
Platonic Yanderes: Rhaenyra, Daemon, Viserys, Corlys, Rhaenys, Joffrey, Rhaena, Helaena, Aegon III, Viserys II, Laenor, Harwin, Alicent and Otto
It may seem strange, but I can see Alicent creating an obsession with Jace when she sees in him the younger version of Rhaenyra, the one who was her best friend and unlike what happened with Rhaenyra, she decides to “save” Jace and do everything to keep him in the path that she considers correct. She sees in him a second chance, and she will be damned if she loses it.
Otto, on the other hand, sees in Jace a way to get what he wants, which is to put Aegon II on the throne and prevent Rhaenyra from assuming her birthright. After all, if Jace and Aegon get married and Aegon usurps his sister's throne, even more people would be willing to support him, since both bloodlines will be united and will continue on the Iron Throne through their children, which would be the perfect solution for the misogynistic lords of Westeros who do not accept a woman on the Iron Throne and to avoid a war, in addition to putting Rhaenyra in a complicated position, against her own son. In his ambition, when Otto begins to observe Jace more closely, he realizes how intelligent and capable he is as an heir to the throne, Otto wishes his own grandson was like that. Later, when his admiration, initially spiteful and then genuine, intensifies, he becomes even more invested in his plans. After all, if Jace is (unfortunately) not his grandson by blood, he will become one through marriage.
Imagine how the Alicent x Rhaenyra and Daemon x Otto conflicts would intensify in this scenario? While Alicent and Otto are extremely invested in "saving" Jace from Daemyra's "vile influence", Rhaenyra and Daemon are willing to do whatever is necessary to free their eldest son from the Hightowers' clutches.
Poor Jace! He would be the center of the war. The greens and the blacks would not just be fighting for the iron throne, but mainly for him.
!! i'm very familiar with the concept of yanderes (it's one of my fav flavors!!🤭) and anon your mind!!😳🧠🤯🤯 i do think out of all of them otto might be the hardest sell/maybe the least attached yandere bc jace definitely has his own opinions, for all that he values outside advice, and otto's main issue with seating daemon or rhaenyra as heir was they were too strong-minded for him to fully control/coral. so yeah i think that would be a point of contention at least early on but you're right and i don't think it'd be impossible to change his mind (jace and his silvertongue is very important to me and i'd love to see it pitted against otto LOL)
PLEASE otto and alicent having delulu saviour complexes abt jace meanwhile daemyra are protective parents goes hard asf fjsk but poor jace😭😭 him being the center of the war would wreak such havoc on his already-present issues and complexes🥹 he's having a terrible time but we! We are having fun! so sry jacaerys my love but you're just gonna have to hang in there💀💕