Question: What happens with Arbor in the final scene?
About the article "The Selfish Giant (2013 film)", section "Plot".

Candidate passages:
The film follows the lives of Arbor and Swifty, teenage boys growing up in an impoverished area of Bradford, northern England.
Arbor suffers from hyperactivity disorder, which often gets him into trouble even when it is not his intention.
When the boys are suspended from school after a fight, they decide to earn money collecting and selling scrap metal.
They quickly realize that stealing copper from telecom, railway, and power utilities proves quite lucrative.
They sell their scrap to a local scrap dealer, Kitten.
Kitten owns a horse and competes in amateur harness racing.
Kitten allows Swifty to work with the horse, once he realizes Swifty's surprising affection for and natural talent with horses.
Kitten also lets the boys borrow the horse and a cart to collect scrap metal.
Arbor is jealous of Kitten's kindness toward Swifty.
Arbor decides to steal a piece of scrap from Kitten and sell it, along with some other scrap, to a dealer in Huddersfield.
The plan ends up backfiring, Arbor is refused at the other dealer and unsuccessfully makes a deal with some men who offer to sell the scrap for him.
Kitten finds out and physically intimidates Arbor into stealing a specific piece of high voltage electric power transmission wire to make up for his loss.
The boys are not fully aware of the dangers of high voltage wire, and when Swifty goes to cut the wire, he is electrocuted and killed.
Arbor is devastated and Kitten is arrested, telling the police he is responsible and allowing Arbor to escape blame.
He sits resolutely outside Swifty's mother's house until, after several rejections, she allows him to hug her and share their pain.
In a final scene, Arbor takes care of the horse Swifty loved.
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The series despite being 'complete' is in fact left with far too many plotholes.
One such being that what happens to the King and the demon realm is never explained, nor is the man, Mutsu, who takes away Ouga.
He claims that he will return before Ura once again, but he does not.
In fact, his first and final appearance is that scene in book 2.
There does not seem to be a sequel for the series, so it is likely that it was simply dropped and claimed to be finished.
The art however, and story concept was beautiful. 
  Harry and Margaret Towsley House (1932), Ann Arbor, Michigan, built for Dow's sister and her husband.
It was the "first residence in the country designed with an attached garage facing the street."
University of Michigan Women's Swimming Pool, Margaret Bell Building (1950), Ann Arbor, Michigan  Ann Arbor Public Library (1955 or 1956), Ann Arbor, Michigan University of Michigan Botanical Gardens (1958), Ann Arbor, Michigan Ann Arbor Community Center (1958), Ann Arbor, Michigan Dunbar Community Center (1958), Ann Arbor, Michigan Leonard Service Station (1960), Ann Arbor, Michigan Institute for Social Research (1960), University of Michigan, Ann Arbor, Michigan  Ann Arbor City Hall (1960), also known as Guy C. Larcom, Jr. Municipal Building, 301 East Huron Street, Ann Arbor, Michigan  Conductron Corporation Offices (1961), Ann Arbor, Michigan University Microfilms Building (1963), Ann Arbor, Michigan Fleming Administration Building (1964), Ann Arbor, Michigan University of Michigan Continuing Education Center (1965), Ann Arbor, Michigan Greenhills School (1967), 850 Greenhills Dr., Ann Arbor, Michigan  
Lesher was involved with the Ann Arbor Civic Theater as a set designer and actor and sang in the Ann Arbor Civic Chorus.