He had claimed to cleanse the politics of politicians 'polluting and ruining' it.
He had promised a politics of change, of high standards, of no compromises, of absolute transparency, of hope, and of what not.
While taking the dip, he sounded like a social activist who was ready to graduate to political activism.
The writings on his political plunge began and sustained with regular mention of 'Kejriwal and the AAP Vs mainstream politicians and political parties' - the entrant Vs the established.
Like it happens, like the 'writing precedents' go, the lot Kejriwal comes from are written as the off-stream (or new stream), heading in to take on the 'mainstream'.
Now, with a self-aborted first term of 49 days, a political foray in its third year, a humiliating loss of face in the general elections 2014, and a second term with a rare electoral win and absolute majority in the Delhi assembly polls, he has started sounding more like the 'mainstream'.
The win, propelled momentously by the BJP's poor show on development parameters in Delhi during the Central rule (February 2014 to February 2015), has, it seems, unleashed the 'mainstream politician' in Arvind Kejriwal, an alter-ego that was waiting to emerge from the shadows.
Like a very seasoned 'mainstream' politician, he stage-managed the ouster of the two senior-most founder members from one of the apex decision making body of the AAP, its political affairs committee. He was in the city, but didn't attend the meeting where his fans inside the party threw the thorns away.
Whatever is the background behind the hostile sentiments of Kejriwal supporters for Yogendra Yadav and Prashant Bhushan, it cannot be denied that these two founder-members would have posed real threat for Arvind Kejriwal's 'mainstream political ambitions'. Among the many demands of them was 'asking Kejriwal to leave the AAP convenor position', a move that would have paved the way for emergence of more power centres in the party with its impending national expansion.
Now, we are well aware of Kejriwal's national and prime-ministerial ambitions, something that could well be the ambitions of many others in the AAP.
Like Kejriwal saw a brilliant opportunity in the half-baked mandate of the Delhi assembly polls 2013, that fell short of majority, to go national, he would have read with certainty that the absolute mandate is a spectacular opportunity to launch the roadmap for the prime-ministerial ambitions again.
For that, he needs to run the AAP the way he thinks, conceives and proposes (and even opposes).
For it, he needs iron grip on the party, removing obstacles (including people), who could question his authority.
For it, he needs a cult around him in his party where he reigns supreme and others follow him verbatim.
And, it looks, he has started it with sidelining Yadav and Bhushan.
Also, like a 'mainstream' politician, he maintained a deliberate and stoic silence while his party was going through the internal churnings.
He left for Bangalore immediately after removal of Yadav and Bhushan from the AAP PAC and spent some 12 days there undergoing treatment for his lifestyle related illnesses, looking (or overlooking) the developments in his party in Delhi and elsewhere.
Tapes and sting-ops came out where Kejriwal was talking like a 'mainstream' politician to score political goals. Tapes also came out that showed his party members snooped on own colleagues. Activists like Mayank Gandhi protested the way Bhushan and Yadav affair was handled by the party. Activists like Anjali Damania left the party alleging (like many others who have left in the past) it had gone off-track. Media analysed the whole panorama day after day. Experts wrote about and thinkers criticised the high handedness.
But, Arvind Kejriwal was not heard all this while.
Like a ripened politician, Arvind Kerjiwal now either doesn't speak or speaks only politically correct, the way 'mainstream' politicians prefer to do.
The developments so far tell us he is well on the way of converting the AAP into a one-man party (like many others in India).
And in the light of the recent developments so far, the 'reported and projected' political pragmatism of taking Congress's support to form the government in December 2013 gives way to the counterpoints that it was always a 'mainstream political move' pushed by political opportunism.
The developments so far tell us the 'mainstreaming' of the politician Arvind Kejriwal is almost complete now.
He is sounding and acting like more and more of 'them' now.
And Kejriwal is fast losing the elements that have given him, so far, the benefit of doubt to still be treated as a political activist, an off-stream politician beginning a political journey within the system, to meet the challenges, to deliver on his promises.