With Mr Shadbolt previously likening their situation to that of Caesar and Brutus, the developing drama has all the ingredients of a Shakespeare play, and the high-profile mayor is promising "blood on the floor".
The final act is set to begin at a special meeting of the Invercargill City Council on Monday to discuss "the removal of Neil Douglas Boniface as deputy mayor".
In late August, council chief executive Richard King was charged with drink-driving.
Mr Shadbolt, who was in Mongolia at the time, said it took several days for Cr Boniface to notify him.
Mr Shadbolt claims his deputy also tried to censor one of his Southland Times columns, which contained an allegation the council communications manager, Eirwen Tulett, the wife of the newspaper's editor, was conspiring to replace him.
Cr Boniface said he could have contacted Mr Shadbolt regarding the drink-driving incident, notwithstanding the fact he was at remote Deep Cove that weekend, but "it was not really my job".
"I don't really feel I have done anything wrong", Cr Boniface said.
When a closed door meeting of councillors in mid-September narrowly elected to retain Mr King - Mr Shadbolt voted for him to be sacked - a deep schism emerged among councillors.
At the time, the mayor said he felt uneasy that he never made Cr Geoff Piercy (79) deputy mayor after the last election, and met Cr Boniface to see if he would move aside for a year and let the outgoing councillor take the position.
Crs Boniface and Piercy both agreed to the offer, but at the council meeting on November 3, Cr Piercy turned down the offer.
Mr Shadbolt said he felt betrayed and moved a motion that he had lost faith in his deputy.
The motion lapsed for want of a seconder, and Mr Shadbolt gave notice under the Local Government Act 2002 that he would call a meeting to discuss Cr Boniface's future.
In the interim, Gore Mayor Tracy Hicks mediated in an effort to heal the rift between the two men.
The Otago Daily Times understands the men agreed to communicate more regularly, define the role of deputy mayor and hold workshops for councillors.
At the conclusion of the meeting, Cr Boniface and Mr Shadbolt shook hands - the pair have not spoken since.
Before flying out on November 13 to Norway on a fact-finding mission on the oil industry, Mr Shadbolt released a statement, after meeting councillors individually, saying "it has now become clear that many councillors want more extensive changes".
The special meeting to remove Cr Boniface, and a subsequent meeting "to review and make changes to council directorships and chairmanships", are scheduled for Monday.
Cr Boniface had been overwhelmed by the support from the Invercargill public since the dispute hit the national headlines, and acknowledged it had helped "lift my profile".
A councillor for 32 years, Cr Boniface has served as deputy for 11 years, or four terms, and "never asked to be deputy mayor".
The position was unpaid until a review two years ago recommended Mr Boniface be paid between $2500 and $10,000 for the position.
He was awarded $2500.
Asked if he was the busiest deputy mayor in the country, Cr Boniface said "I think that would be fair", but quickly qualified his statement.
"The mayor is one of the hardest working too, with all his promotion and PR stuff," he said.
In periods of Mr Shadbolt's absence, Cr Boniface has stepped into the role of acting mayor on seven occasions, including appearances at a function in Bluff, the local Santa Parade and a Special Olympics event.
"I don't mind. I love doing what I do. I love making a contribution," he said.
Cr Boniface, who once contested the mayoralty, in 1993, following the death of former mayor Eve Poole, said "I did have aspirations to be mayor, but no longer."
He feared efforts to remove him and change directorships and chairmanships had the potential to undermine much of the good work achieved for the city, which had enjoyed a remarkable turnaround in terms of population and business fortunes over the past decade.
It appears Cr Boniface has the numbers to retain the deputy mayoralty, and councillors also indicated no-one would be willing to accept the "poisoned chalice" if he was removed.
However, several councillors said they feared a "lolly scramble" for directorships and chairmanship roles, following rumours of back-room deals in exchange for support at the council table.
One councillor said legal action was a possibility if people were stripped of their roles.
Cr Darren Ludlow said he hoped his fellow councillors would declare their positions at the meeting, so the public, at the very least, knew where they stood.
Cr Norman Elder said he wanted the mayor to withdraw his proposal, to reconsider his position on Cr Boniface and to change chairmanships.
The issue reflected poorly on the city at a "critical period in our history", with possible investment in oil, gas and coal exploration, the growth in dairy farming and a burgeoning biotech industry all in the pipeline, he said.
Cr Piercy said during his 14 years as a councillor the council had been relatively settled, but recent events to replace long-serving councillors were "rotten".
"Absolutely rotten, and you can quote me on that."
