The combination of Ash needing to make a monthly payment to his father to purchase the garage (which finances his parents' Florida retirement), a well-financed competitor engaging in predatory pricing in an attempt to put Ash out of business, along with now having to care for Isla, has made finances very tough for Ash. Isla is very small for her age and a poor student (both of which were likely due to parental neglect; Isla is one year behind her age-peers in school) who has no friends and is usually criticized by her teacher for her poor academics; however, she is very talented artistically.
Of the three siblings Heather is the most quickly drawn toward both the parent and the child, but Ash's very reserved nature (due to growing up in a home with very little outward affectionever shown, even between his parents) makes him extremely hard to judge as to how he is feeling about things, especially Heather's repeated visits to the garage to help Isla with her homework(and later helping Ash take care of Isla's hair), and Hunter's business proposal to help the garage. But wanting to give Isla what her mother didn't (and having no clue how to raise a child, especially a girl), he is willing to accept the Kings' invitations and generosity; , as Isla's interactions with Rachel provide the family help her greatly (notably, Rachel becomes the friend she Isla has wanted so badlysince moving to the Twin Cities).
As they interact with the Kings, both Heather and Ash notice something unusual with Isla: she has somehow learned what to do when someone is praying (bow her head and fold her hands), the real reason for Christmas and Easter (Jesus), and despite her dislike of reading has managed to memorize [[John 3:16]]. Ash knows that neither he nor Gwen taught her that (they grew up in an irreligious home and continued that into adulthood), but later learns from Isla that Donna, a neighbor of Gwen, often cared for Isla on weekends (and when Gwen was drunk or high, or "sick" as Isla put it; it was Donna who discovered Gwen's body) and took her to church. After attending Rachel's church pageant, Isla also wants to attend church there, to which Ash agrees (remembering how his parents repeatedly caused Gwen disappointment and discouragement at her interests). When Hunter and Ash go to pick up Hayden for Christmas Eve activities, Ash tells Hunter that since Isla was never a priority for her mother, she is a priority for him; Hunter responds that Ash should not be blind to someone who also wants to make Isla a priority (Heather), and that (because of Rachel's and Isla's budding friendship) they are for all intents and purposes "part of the family". At the Christmas Eve service the pastor repeats John 3:16, which has Ash thinking about Christianity; he asks Hunter to explain things, and ultimately he becomes a Christian.
Like Carissa felt with Hunter, Ash feels a relationship wouldn't work between Him and Heather due to their disparate statuses in life, while Heather is unable to get any idea on how Ash feels about her due to his inability to express his feelings. However, the two are able to work out their concerns, and begin dating (they agree that Ash will pay for dates and go to non-chain restaurants which he can afford). In the subsequent books, Heather and Ash are engaged, they marry (on a tropical Pacific island) and enroll Isla in the same school as Rachel, and ultimately they adopt Isla as their own daughter. Isla also discovers a singing talent: she and Rachel perform a duet in the following year's children's Christmas pageant at church.