Relationship between Keyleth and Vax'ildan

Humble Beginnings
In the swamp town of Stillben due to a chance encounter, Keyleth and Vax'ildan first met as fellow hired adventurers in the group that later became known as Vox Machina when they banded together along with Vax's sister Vex'ahlia (and Trinket), Grog Strongjaw, Tiberius Stormwind, and Scanlan Shorthalt. Their first job led to the group having to fight Crysa-Thul, a stillborn god, the contract they took having been a ruse to feed the party to this god. They managed to survive and deal retribution to Fendril Vas, the man who contracted them in the first place. From there, through their many subsequent adventures while exploring the highs and lows of the realm of Tal'Dorei, the two half-elves became close friends.

Realizations Within the Underdark
During their time in the Underdark, after having defeated Queen Ulara, Keyleth brought up her suspicions about Lady Kima of Vord and why she sought the Horn of Orcus that K'Varn possessed. As she went on with her arguments, Vax gleaned a deeper meaning from them, noticing something about her as she argued. When Clarota suggested that Vox Machina take Kima back to the surface, as they originally intended, due to the paladin's volatile personality, Vax objected, saying that it wasn't fair. He then told the druid that he knew about her hardships, that they all have had them, and that they have all made mistakes. Keyleth subsequently broke down in tears, wondering if they were doing the right thing and upset that she killed a lot of people. Vax, along with Percy and Tiberius, went on to mention that despite the situation in which they found themselves, miles underground, they were the only ones that could put a stop to K'Varn's plot, and that they would get through their ordeal together.

Developing Emotions
It was during their time in the Underdark that Vax began developing deeper feelings for Keyleth,   and over time, those feelings gradually became stronger. As for Keyleth, Vax's support of her and her moral outlook—as well as the commonality of their desires to remain true to their ideals—caused her to develop feelings for him. During their journey to Vasselheim, Vax insisted on helping her with scroll-making. During their "Trial of the Take", in order to infiltrate The Velvet Cabaret alongside Tiberius, Thorbir Falbek, and Kashaw Vesh, the five decided to adopt aliases. Vax took the pseudonym "Lord Scanlan of the Emon Shorthalts" and, as a suggestion to Keyleth, asked if she would be his "wife", which led to an awkward pause from everyone. Keyleth accepted the "proposal" and took the alias "Quaraline Shorthalt".

When it came time to travel to Pyrah for Keyleth's Aramenté trial, Vax was in strong support of it. When Keyleth opened a portal into the Elemental Plane of Fire and dove in, despite his phobia of lava from nearly having his foot melted off, Vax conquered his fear and followed after her.

During his near-death experience when he first encountered the Briarwoods, as his life flashed before his eyes, Vax thought of Keyleth as being "beautiful, walking under the trees". Vax later finally revealed to the druid, after almost dying again at the hands of Professor Anders, that he was in love with her and emphasized it with a kiss. Vax's sudden display of affection greatly flustered Keyleth, and she later admitted to having some feelings for him as well, but she revealed that she was afraid of pursuing the relationship. Vax agreed to "wait for her", to give her the time she needed to make her choice as to whether or not she wanted him.

As their adventures continued and after the trauma of the Chroma Conclave's attacks across the world, Keyleth became increasingly receptive toward Vax's companionship. When Vax departed from the underground shelter beneath Shaun Gilmore's shop, Keyleth tried to stop him from going after Vex, but the older twin refused to leave his sister alone. When Vax, Vex, and Scanlan eventually returned to Greyskull Keep from a failed attempt at finding Thordak's hoard, Keyleth immediately ran to the rogue and embraced him, relieved that he was safe.. The following night, Keyleth and Vax both voiced their disapproval of an alliance with The Clasp and, as a sign of him severing all ties with the guild, Vax asked Keyleth to burn away the brand on his back. Keyleth complied and did so with her burning hand, leaving in its place a scar of her handprint. Before retiring for the evening, when Vax knocked on her door and said he didn't want to be alone for the night, Keyleth admitted that she hadn't been wanting to be alone most nights, allowing him into her room. Keyleth even made the conscious decision to kiss and hug Vax in front of everyone after Grog's test of character against Earthbreaker Groon in Vasselheim.

A Fractured and Fragile Bond
After Vex was killed and resurrected during their search for the Vestiges of the Divergence, Keyleth later explained that she was scared of losing Vax. While she thought she loved him, she felt too terrified to allow herself to explore that love because she feared outliving and losing everyone once she completes her Aramenté. Unable to handle this new revelation, Vax exited the room, leaving behind a sobbing Keyleth.

Despite this revelation, the two still cared deeply for each other. In the middle of preparing for the battle with Umbrasyl in the city of Westruun, Vax apologized for leaving her side that night. As for Keyleth, she later mentioned how uncomfortable she was about having to potentially depend on the gods for assistance. Despite the tense conversation, they later shared a kiss that night in case they died the following day. When Vax and Scanlan went into the dragon's stomach and he flew off, Keyleth in desperation used the Gate Stone to try to get to him.

The Raven Queen
Despite Keyleth's views on the gods providing further complications between them, she later had a talk with Vax where the rogue wanted to have a meeting with the Raven Queen in Vasselheim. She agreed to come with him along with Pike. After his "communion" with his patron, Keyleth and Vax had a mild argument about whether or not Vax's ordeals over the past few weeks were fate or something that he really wanted and that it found him. And in the middle of their discussion, she told him that the Vax she knew was no different than the one that had undergone the communion, that the Raven Queen didn't need to make him special; he already was in her eyes. She did tell him, though, that she believed wholeheartedly that what he experienced was real and true.

The Feywild
Around the time that the party decided to go to the Feywild—and after receiving encouragement from her father Korrin, Vex, and Pike—Keyleth started to realize that her earlier fears were ultimately unfounded, purely based on an unwritten future. Due to this realization, she started to allow herself to be more comfortable in Vax's company as per Pike's suggestion. While within the Moonbrush, Keyleth decided to scout ahead and spy on the wisher pixies. Upon hearing from Vex that she went off on her own, Vax immediately took flight after her. Upon slaying the pixies that later attacked them, she expended a high-level Greater Restoration to cure Vax of petrification.

And just before leaving the Feywild after retrieving Fenthras, Vax remarks how amazing she had been, which Keyleth returns in kind.

Facing One's Fears
Keyleth gained a new perspective on her concerns about a future with Vax in the aftermath of finding Tiberius's body in the ruins of Draconia, with her dragonborn friend having been killed by Vorugal. Keyleth said her farewells to Tiberius and buried him. Upon returning to Whitestone, she eventually went to Vax's room and insisted on being with him for the night. As Vax poured his heart out to her and expressed his doubts about the two of them and where they stand, Keyleth interrupted, telling him about her conversation with Pike and the realization that they ultimately had "nothing to lose." Then she finally confessed that she loved him—and had for a long time—and apologized for taking so long to say it. Vax admitted again that he loved her as well, and they started spending their nights together ever since.

After witnessing Keyleth nearly die in battle against Anna Ripley and her henchmen on the Isle of Glintshore, and after Raishan made her presence known to them in Whitestone, Vax voiced his fear of losing her and his thoughts about her extended longevity should she complete her Aramenté. Nevertheless, he wanted to ensure that it would happen.

After killing Vorugal, Vax objected to Keyleth's desire to go after the Diseased Deceiver right away without the others, convincing her that they needed the rest of the party to do it and assured her that they wouldn't have to wait long.

In the middle of their battle with Ghurrix in the City of Brass, seeing Keyleth wounded, scared, and alone in the middle of the street, Vax flew down and kissed her, casting Heroism at the same time, to give her the courage and bravery she needed to see the battle through. When the battle finished, he hoisted Scanlan onto his shoulders and celebrated the heroism of both the bard and Keyleth. Despite her hesitancy and refusal of thinking herself to be a hero, Vax insisted that she deserved the praise.

Thordak and Raishan
On the night before Vox Machina set out to return to Emon to face Thordak, Keyleth took Vax and Allura Vysoren to her hometown of Zephra to enlist the aid of her people. It was then that she was reunited with Korrin, who told her that he and his fellow druids would be joining the battle as well because he did not want to stand by and do nothing while his only daughter was out there fighting. Vax mentioned that Korrin was a good man, to which Korrin asked that Vax prove to him that he is as well. And as Korrin departed, Vax pulled Keyleth aside and told her before they returned to Whitestone, "I can't wait to come back."

In the aftermath of the battle with Thordak, when Raishan planned to fulfill her end of the deal and extract her information from the Cinder King's corpse, Keyleth told Vax to wait for her before doing anything. When Raishan began casting Speak With Dead due to a scroll, in his desperation to stop the dragon from fulfilling her goals, Vax attacked the Diseased Deceiver. Alas, his efforts were futile as the spell was successfully cast and, after being told that she would not leave Thordak's lair alive, Raishan flew further in, forcing Vax, Keyleth, and Vex to pursue and nearly get wiped out by the dragon's Meteor Swarm spell. In more than one instance, Vax's life was in peril during the brutal battle with Raishan and Keyleth did what she could to keep her lover alive, even though she nearly died herself when attempting to cross a river of lava. Despite the party's best efforts, the dragon ultimately escaped with Thordak's corpse in tow, the pair's vow to slay her unfulfilled. After the battle, Keyleth expressed that both she and Vax deserved to bear part of the blame, but Vax told her that they did what they had to do in order to attempt to stop the dragon from fulfilling her goals.

Later, before going to bed in Castle Whitestone, Vax tended to the remnants of Keyleth's charred and shortened hair, gently cutting away the burnt ends. He then told his lover that her new hairstyle looked good on her. He also comforted her and told her that he had seen her growing strength, that she was doing the best she could with what she was given and that she had never backed down. He also told her that despite her growing doubts, she needed to mix them with Vax's faith in her as well as everyone else's faith in her. Keyleth then confessed that Vax and the rest of Vox Machina were her first and longest-lasting friends and that they were family to her. They then both promised to go with the other to wherever they wished once everything was behind them: Keyleth with Vax to "the theater" and Vax with Keyleth to Zephra. After slaying Raishan and burying Senokir's wife's ashes in the Abundant Terrace as he requested, Vax and Keyleth later planned to go on a proper date by going back to the Velvet Cabaret in the future in order to spend some time together before the Raven Queen puts Vax to work.

Aramenté's End
En route to Vesrah, the party was attacked by a pirate crew. During the fight, Vax once more expressed his admiration towards Keyleth's powerful magic. Vax and Keyleth later took the time to reconnect and talk about her upcoming test with the Water Ashari as well as her fear of losing her friendship with Percy to that of Taryon Darrington. After speaking with the headmaster and eating a Heroes' Feast in preparation for their venture into the Elemental Plane of Water, they talk about leadership and doubts, comparing Uriel to Keyleth's future as headmaster of the Air Ashari. Vax then pulled out his wings, saying to Keyleth, "We have one hour", before they... retired for the evening. During the search for the lodestones, the party accidentally attracted the attention of a nearby kraken. On more than one occasion, both Vax and Keyleth found themselves grappled by the creature's tentacles and, on separate occasions, were swallowed whole. Keyleth managed to get herself and Grog out of the creature's stomach. Vax, however, was not as lucky as his body went limp upon being swallowed. Despite Grog's successful attempt to get both him and Vax out of the kraken, it was already too late as Vax's life was snuffed out right before Keyleth's eyes. In desperation, Keyleth grabbed his cold hand and that of Vex who was nearby and cast Plane Shift to get the three of them back to Vesrah. She later took part in the resurrection ritual where she reminded him of the promise they made to each other to settle down and live happily together. She then cast Daylight into the scar on his back that she had given him and echoes his confession to her: "And besides, you know I'm in love with you, right?" Vax was later successfully resurrected. Vax then accompanied Keyleth back to Zephra where she was then given the mantle of leadership and became the new Voice of the Tempest and therefore the new headmaster of the Air Ashari. During her speech, she mentioned all of Vox Machina one after another, where upon mentioning Vax she says, "Vax is one of the most compassionate people I think I’ve ever come across and one of the most brave, even if it’s maybe foolish."

Loose Ends Before the End
During their venture into the Nine Hells to destroy Hotis, Keyleth found herself accosted by a misshapen dwarf and a chain devil, the two of them insisting that she hand over "the white one". She figured that they were referring to Vax, so she outright refused, stating that he belongs to her. When they didn't buy into her claim, she Shapechanges into an erinyes to intimidate them and have them back off. Vax and Keyleth—along with the rest of the party and a dwarven lycanthrope named Tova—later engaged the pit fiend Utugash in his home. During the battle, Keyleth found herself pinned and badly wounded by the pit fiend as Vax tried in vain to get him off, thus forcing her to Shapechange into a massive fire giant and choke-slam Utugash, Vax remarking once more how awesome she is.. When they later found themselves imprisoned within Mentiri, Keyleth freed herself from her shackles and used her Thorn Whip to retrieve Vax's lockpicks so he could get himself free. During their escape, Keyleth found herself at death's door once more, and upon realizing that her death would have left the party with no way out of the Hells, Vax rushed to her side to help get her conscious again. Upon safely returning to Whitestone, after a lot of drinking at a local tavern, Vax and Keyleth discussed the future in addition to Vax wanting to talk to Vex about separating for the time being and when the Raven Queen may cash in on the deal Vex had made, as well as once more expressing how much they love each other. Vax later chose to follow through on his promise to Keyleth and for the next year returned to Zephra with her.

Vex'ahlia's Reactions to Keyleth and Vax'ildan's Relationship
Vax didn't talk to Vex'ahlia (his twin sister) about his love for Keyleth, which caused some tension between them. For the most part, Vex also seemed to resent their potential relationship initially and made a point of disturbing their private moments. When they returned to Vasselheim, she teasingly reminded them that Kashaw had kissed Keyleth. When Kashaw returned to Keyleth's life, however, Vex wasn't as resentful as expected and instead tried to encourage the druid to make her move with Vax, which she did when she openly kissed him after Grog's test of character against Earthbreaker Groon.

Vex continued adjusting to the reality of her brother's feelings, and after the party survived the slaughter of Umbrasyl, she asked Vax what was going on with him and Keyleth, but Vax refused to answer. Vex then asked how Keyleth feels about him, and Vax replied, "Ask her." So, Vex promptly asked Keyleth, who reluctantly admitted to having feelings for Vax and asked if Vex would hate her for that. Vex, after her death and resurrection, however, was no longer resentful and encouraged the druid to just be happy and not live in fear. Since then, she continued teasing her brother and Keyleth about their relationship, but she also stopped showing any further resentment, admitting to Keyleth that she cares.