During the week of Halloween, the Intelligence Unit was engaged in an investigation concerning three women discovered behind a dumpster, each suffering from multiple stab wounds. As the team sought to establish any links among the victims, Billie was in the break room retrieving a bottle of water when Hank entered and inquired, "I was hoping you could take a look at this note; I believe it is in an Indian language, and it was found near the victims." Billie examined the note and responded, "It is indeed an Indian language, but it is not Cherokee, so I am unable to interpret it. However, I know someone who can." Hank then asked, "Who is that?" Billie replied, "Chief Flying Wolf from the Indian reservation; he is proficient in all Indian languages. Would you like to accompany me for a visit?" Hank, Billie, and Riker then entered Hank's vehicle and headed towards the reservation. During the journey, Billie shared insights about the reservation's history, stating, "Chief Flying Wolf has lineage from every Indian tribe, which enables him to understand all Indian languages. He established the reservation to unite all Indians, refusing to let tribal differences create divisions. I spent my childhood summers there." Upon arriving at the reservation, they parked in front of the police station, where Billie greeted the officer at the desk with, "Howdy, Running Bird." Running Bird looked up and replied, "Red Wolf, it has been some time," as he embraced her. Billie introduced Hank, saying, "Running Bird, this is Sergeant Hank Voight. We are here to consult with Chief Flying Wolf regarding a piece of evidence." Running Bird informed them, "He is located on Snakehead Hill; today is Tribal Heritage Day." Billie turned to Hank and asked, "I trust you have experience riding a horse?" Billie and Hank mounted a brown horse named Bo, with Riker trotting alongside, while Running Bird rode a white horse named Snowflake. Observing Hank's nervousness as he held onto Billie's waist, Running Bird noted the unspoken feelings between them. Upon reaching Snakehead Hill, Hank was captivated by the array of Indian artifacts and the presence of individuals from various tribes. Upon arriving at Chief Flying Wolf's tent, a young 20-year-old Native American stood outside and greeted them with, "Hello, Red Wolf." Billie responded, "Sly Fox, may we speak with your grandfather?" Sly Fox entered the tent briefly before emerging to confirm, "Yes." Billie and Hank then entered the tent, where Chief Flying Wolf welcomed them, saying, "Red Wolf, it is always a pleasure to have you visit. How may I assist you today?" Billie replied, "We are hoping you can help us understand this note." Chief Flying Wolf examined the note and explained, "It is written in the Cheyenne tribal language. It translates to 'Catch Me If You Can, You Are the Cat, I Am the Mouse.'" Billie and Hank expressed their gratitude, and Billie embraced him, introducing, "This is my Sergeant, Hank Voight." Hank extended his hand for a handshake with Chief Flying Wolf. Subsequently, they, along with Running Bird, rode back down the hill, with Riker leading the way. Billie shared a hug with Running Bird, and together, she, Hank, and Riker made their way back to the station. The team apprehended the suspect two days prior to Halloween, who was identified as a young man from the Cheyenne tribe. After completing some paperwork, Billie and Riker proceeded to Hank's office, where Billie inquired, "Would you like to go for a drink?" Hank consented, and they made their way to Molly's bar, engaging in casual conversation. Billie then shared, "I come from a family of first responders. I have two brothers, Steve and Danny, who are part of a task force known as Five O in Hawaii. They use their middle names, McGarrett and Williams, to prevent any confusion between them. Danny has two children, Gracie and Charlie. Additionally, I have an uncle, Dwayne, and a cousin, Christopher, who are employed by NCIS in New Orleans, and they also utilize their middle names, Pride and LaSalle, for clarity. My uncle Jethro, along with his children Tony, Abbey, and Tim, works for NCIS in Washington, D.C., using their middle names Gibbs, DiNozzo, Sciuto, and McGee. His son Nick is in the Army and was fortunate enough to be stationed there. I also have two friends, G. Callen and Sam Hanna, who serve with NCIS in Los Angeles. My stepbrothers, Marcus and Tristan, are detectives for small towns; Marcus and his husband Lenny have twin boys. My other stepbrothers, Mitchell and Mikey, are firefighters in Hunt, each married with two children. My stepbrother Rufus and my half-brothers Kyle and Cash serve in the Army part-time, while my other half-brothers, Cooper and Thomas, are professional singers. My grandfather served in the Air Force, and as a family, we perform as an acappella group." Hank remarked, "That is truly remarkable." Billie responded, "You know, I am 26 now, yet I still do not know your age. I have been trying to determine it since we first met in 2014." Hank chuckled softly and replied, "I am currently 55; my birthday is just eight days before yours, on the 12th of March." Billie commented, "For someone who is 55, you certainly maintain your vitality." Shortly thereafter, they approached their car, where Riker awaited Billie, his nose poking through the gap in the window. Hank and Billie embraced, and as they released each other, they exchanged lingering glances, both acutely aware of the chemistry between them. Billie then said, "Goodnight, Hank," and they each entered their vehicles, departing for their respective homes. Upon arriving home, Hank indulged in thoughts of Billie, unaware that she was similarly engaged in her own private moments, thinking of him.
In June 2016, Hank faced an immense tragedy; his son Justin had been murdered in May. To compound his grief, his daughter-in-law Olive took his grandson Daniel and left, leaving Hank in solitude. Although Billie had been respecting Hank's need for space, she sensed that he required someone to confide in. Before departing from work, Billie decided to visit Hank's office, with Riker following closely behind her. She inquired, "Are you alright?" Hank responded, "Yes, just lost in thought." Billie explained, "I haven't been avoiding you intentionally; my parents taught me to allow people their space during times of grief." Hank acknowledged, "I understand; I knew that was your intention." Billie approached him and embraced him, assuring him, "If you ever need to talk, I am here for you." Hank then proposed, "Would you like to join me for a drink at Molly's?" Billie accepted, and she and Riker met Hank at the bar. Inside, Riker settled beside Hank, resting his head on Hank's lap, a gesture he typically reserved for moments without his service vest. As Billie and Hank engaged in casual conversation, she unexpectedly brushed her hand against Hank's thigh. Startled, she quickly withdrew her hand, and they exchanged a glance, with Billie apologizing, "I'm sorry, I don't know why I did that." Hank reassured her, "It's alright; I don't mind." Although unspoken, both felt a surge of emotions beneath the surface. Shortly thereafter, Cooper messaged Billie, stating, "Owen has a fever and is asking for you." Billie informed Hank, "I need to head home; Owen isn't feeling well." Hank accompanied Billie and Riker to her car, where they shared a hug. During the embrace, Hank inhaled the scent of Billie's hair. When they separated, Hank stammered, "Oh, um, I didn't mean to do that." Billie smiled and replied, "It's fine." Once again, they sensed their emotions intensifying. They bid each other goodnight and drove home to their separate residences.
The following week at the office, the team was engaged in a challenging case involving a three-day-old infant discovered in a dumpster. This case resonated deeply with Hank and Billie; Hank was still grappling with the recent loss of Justin, while Billie recalled the painful moment when she learned of her miscarriage involving her son Owen's twin. Both were determined to uncover the individuals responsible for this tragedy. Billie stepped into the breakroom to fetch some water, and Hank soon joined her. He gently placed his hand on her shoulder, prompting her to turn around. Hank appeared anxious as he expressed his gratitude, saying, "I want to thank you for being there for me since Justin's death." Billie replied, "No problem, I know you'd do the same for me." They exchanged glances for a few moments, leaning in as if to kiss, but were interrupted by Jay's sudden entrance, causing them to startle. Jay announced, "We have a lead on the parents; we have their address." The team quickly made their way to the location. The mother complied without resistance, with Jay Halstead and Erin Lindsay taking her into custody, but the father fled down the street. Billie and Riker pursued him while Hank drove after them. When the father turned around and saw Riker, who was snarling and foaming at the mouth, he attempted to escape more quickly, but Riker caught up and bit into the man's leg. The man collapsed, and Billie instructed Riker, "Release, Riker." She swiftly handcuffed the man as Hank and the rest of the team arrived. Jay placed the man in the back of his vehicle. Kevin hurried to Billie, inquiring, "Are you okay?" to which she responded, "Yeah, I'm fine." Billie and Riker then got into Hank's car, and the team returned to the station. It was not long before the parents confessed to the murder of their child, explaining, "The baby was crying, and we just couldn't take it anymore, so we smothered it with a pillow, and after it was dead, we discarded it in a dumpster." After the parents were processed, Kevin inquired of Billie, "Would you like to go to Molly's for a meal?" Observing Hank's gaze, and aware of her concealed emotions for him, Billie replied, "I appreciate the offer, Kevin, but I think I will head home." Unbeknownst to Billie, Kevin harbored feelings for her, just as Kevin remained unaware of the mutual feelings between Billie and Hank.
By September 2016, the relationship between Billie and Hank had deepened significantly. They frequented Molly's bar each evening after work, unaware that their feelings for one another were intensifying. One night, they attended a police gala where Billie donned the same alluring dress she had worn during their first meeting at a similar event in 2014, this time she had a new addition to her body, she had added a dog collar around her neck. Seated at a table with a plate of sliced cucumbers and tomatoes, accompanied by a glass of white wine, Billie was nudged by Riker, her dog, prompting her to share a cucumber with him; he was the only canine she knew who enjoyed vegetables. Shortly thereafter, Hank joined her and inquired, "How are you this evening?" to which Billie responded, "I'm good." As Elvis Presley's "Can't Help Falling In Love" began to play, Hank extended his hand and asked, "Would you like to dance?" Billie accepted, and they swayed gently together amidst the other couples. Hank expressed, "After my wife Camille passed, I never imagined I would encounter someone who could bring light back into my life, but you have done just that." Billie replied, "I once believed I would only meet men who were interested in fleeting encounters, but knowing you has shown me that not all men are like that." Their gazes locked, charged with emotion, and Hank remarked, "What I admire most about your dress is how it accentuates your features. I appreciate your confidence in your body and your willingness to showcase your tattoos, curves, and piercings without fear of judgment, even though your dress offers minimal coverage." Billie smiled and responded, "Well, Hank, you look quite attractive in jeans, and your raspy voice is a particular allure for me." As the song concluded, Billie suggested, "Shall we leave? There's a diner called Murphy's that stays open until 2 a.m. and serves fantastic milkshakes." Hank agreed, and Billie called for Riker. Riker trotted along side Billie and Hank as they walked to their cars, and Hank followed Billie's car to Murphy's Diner. Kevin approached the table where Jay, Erin, Adam, and Kim were seated and inquired, "Do you know where Billie is?" Adam responded, "She mentioned something about heading to Murphy's Diner earlier at work. Why do you ask?" Kevin replied, "I intend to ask her if she would be my girlfriend." Meanwhile, Billie and Hank were seated at an old-fashioned round table near the cooking area, enjoying fried pickles while the owner and head chef, known as Kenny, prepared their meals. Billie shared the history of Murphy's Diner, stating, "Kenny's grandfather, Murphy, established this diner in 1957 at the age of 37 as a tribute to all the men and women who serve our country, providing a place for military personnel and their families to enjoy a meal and socialize. Kenny's father, Murphy Jr., took over the diner in 1990 after his father's passing, and Kenny assumed ownership in 2013 after Murphy Jr. passed away. My parents used to bring us here when I was younger, and my grandparents brought my mother and uncles here during their childhood." Kenny interjected, "Billie often brings her children here." Shortly thereafter, Kenny placed their food in front of them and handed Billie a plate of lamb fries to give to Riker. After taking a bite of his burger, Hank exclaimed, "Wow, this is an excellent burger! What type is it?" Billie answered, "It's a Cajun buffalo burger, served with Cajun ranch French fries." Kevin arrived at Murphy's and walked toward the entrance, contemplating how to express his feelings to Billie. However, upon peering through the window and observing Billie and Hank at the round table, laughing and sharing a moment, with Billie gently caressing Hank's face, Kevin realized he might be too late to confess his feelings. He returned to his car and drove away. After finishing their meal, Billie ordered two whiskey milkshakes for herself and Hank. Hank was captivated by the milkshake and consumed two more, becoming slightly intoxicated but not to the extent that he could not speak or walk. After Billie settled the bill, she, Hank, and Riker exited to their vehicles. Hank inquired, "May I stay at your place tonight? I would prefer not to be alone." Billie consented and proceeded to attach Hank's car to her own, as she did not want him driving while slightly intoxicated. They arrived at her residence at 11:30 PM, where everyone else was already asleep. They ascended the stairs quietly, with Riker resting downstairs alongside the other pets. Upon entering her room, Billie closed the door, and Hank was taken aback by the array of dildos prominently displayed on her dresser. He remarked, "Wow, it seems you have a fondness for adult toys." Billie replied, "Yes, it's somewhat of an addiction." As rain began to fall outside, it created an intimate atmosphere. Hank gazed out the window at the sky, and when he turned back, he was astonished to find Billie had removed her dress and stood before him nude, revealing her beauty. Sensing Hank's myriad thoughts, Billie approached him, took his hand, and placed it on her left breast. They locked eyes and soon succumbed to their feelings, sharing a passionate kiss. Soon, Hank found himself unclothed as well. Billie gently guided him to lay on her bed, where she began to passionately pleasure him orally. Hank moaned softly, instinctively guiding her mouth further down his penis. After a brief period, Billie lay on her back, and Hank reciprocated by pleasuring her orally, his fingers deftly working her pierced clitoris. He soon transitioned to sucking on her breasts, teasing the small chains that adorned her nipple piercings. Hesitation briefly crossed Hank's mind before he proceeded to insert his penis into her vagina, but Billie reassured him with a gentle caress and a soft, "It's okay." Hank penetrated her slowly and tenderly, their bodies moving rhythmically in unison as they shared passionate kisses. Conscious of not waking anyone, they kept their passion quiet. At Billie's request, they shifted to try anal penetration. She asked Hank to attach a leash to the dog collar she wore around her neck and to pull tightly. Hank complied, and after securing the leash, Billie positioned herself on all fours on the bed. Hank carefully penetrated her anal region, his movements becoming more vigorous as he pulled on the leash, causing her to choke slightly. The sound of her gagging heightened his arousal, and he accelerated until he neared climax. Releasing his grip on the leash, Billie expressed her desire for him to finish in her mouth. Hank obliged, moaning as he watched her swallow his ejaculate. Afterward, they lay together on her bed, Hank gently tracing his fingers over the tattoos on Billie's stomach. Reflecting on their newfound intimacy, Billie remarked, "I can't believe it took us this long to make our feelings known." Hank replied, "I'm glad we finally expressed our feelings for each other, despite the age difference." As the clock struck 1:00 AM and the rain continued to fall outside, Billie and Hank cuddled closely and drifted off to sleep.