TW: Mentions of Violence & Death, Emotional Manipulation, Toxic Mindsets.
A.N. - Based on his Monkey King Reborn counterpart but has elements of the 16th-century novel.
Platonic:
When Sun Wukong deems someone an enemy and strikes them in defence of his friend, it often becomes Tang Sanzang's job to coach him back to a peaceful state of mind. Sanzang repeats to him that monks are creatures of temperance and should not be so desperately invested in any one relationship. Wukong struggles with the idea of, in his opinion, giving up a person who sees him as he deserves to be seen when such respect is in short supply.
Regardless of the truth, Wukong views his friend as one of the few who gives him the appreciation he is owed. This favour is repaid by way of inspecting anyone who approaches them and stopping the conversation with demands for the individual to take their disrespectful carcass out of his sight if Wukong gets the impression that they are being disingenuous or are insulting his friend. He is sensitive to rudeness because he has endured so much of it, and watching his friend endure the same is among the fastest ways to provoke him into a fight.
In addition to acting as a protector, Wukong has looser morals than Sanzang would prefer to admit and is inclined to steal anything that his friend wants or needs. His status as a trickster god and the past instances of deities shaming him for existing and wishing to be included have made him indifferent to most rules. Wukong sees no gain from obeying people who dislike him for reasons out of his control, and he instead finds pleasure in sharing material desires with his friend in exchange for praise.
Since his time in the forests of Mount Huaguo, immortality has been a great source of curiosity for Wukong. This desire to prolong his life is extended to his friend, who he wants to accompany him through the journey no matter what laws of nature he must break. Because Wukong enjoys eternal life, he assumes that they will as well or at least will come to appreciate it over time. Wukong jokes about making his friend immortal to gauge their willingness, but if they are ever in danger of imminent death, he pursues the Peaches of Immortality and Grass-returning Cinnabar with a degree of ruthlessness that ignores all complaints and exterminates all obstacles.
Romantic:
Even though his physical abilities surpass those of almost every other being in existence, Wukong is a frequent victim of envy. He strongly believes that he is not given his dues both by his fellow deities and the general population. Zhū Bājiè and Shā Wùjìng are initially quite interested in meeting his partner, but they come to learn that Wukong grows moody and a bit hostile when his partner's time and attention are occupied by someone else.
It takes a long time for Wukong to let his guard down with the world, but before this changes, he is convinced that his partner is under constant threat from demons, humans, and deities alike. He is quick to defend them in arguments and take the blame for whatever caused the disagreement, resorting to threats and his shapeshifting staff Ruyi Jingu Bang to ward off the aggressor. Once Wukong is riled enough to engage someone in combat, he tends not to stop until his opponent is either buried in the ground or begging for forgiveness.
Wukong comes close to treating his partner as an equal. He does hold them in higher regard than he holds all others except his master, but due to his short temper, this is often expressed in less than charitable ways. A recurring method is to attack those who Wukong suspects of meaning his partner harm without offering his partner an explanation until the person, who he claims is possessed by a demon, is beaten or even dead.
Sanzang worries for the health of his disciple and encourages Wukong to restrain his darker impulses. These teachings are more effective when his master is around to chastise him, for Wukong is eager to avenge any perceived wrongs done to himself and his partner. The instructions to control his emotions only push him to act in the shadows and play innocent near Sanzang, which is tested every time Bājiè has the urge to report Wukong's attacks and widespread antagonism to their master.