Pashupati Kumar Paras has now staged a coup that has left Chirag Paswan isolated.
Signs of a split in Chirag Paswan's Lok Janshakti Party (LJP) first emerged last year when he publicly told off his uncle Pashupati Kumar Paras, sources say.
Mr Paras, the younger brother of LJP founder and Chirag's father Ram Vilas Paswan, had always been his Man Friday, preferring to be low key. When his nephew took control of the party, things soured quickly.
The Hajipur MP has now staged a coup that has left Chirag Paswan along and isolated in his own party. The remaining five MPs have gone to the Lok Sabha Speaker and asked to be identified as a separate group.
Chirag Paswan drove to his uncle's house this afternoon for a possible reconciliation, but waited in his car for an hour and 45 minutes before he was forced to leave. Mr Paras did not invite him in or make any move to speak to him either. Some reports said he was not in.
Their hostilities peaked eight months ago.
Four days after Ram Vilas Paswan died on October 8 - weeks before the November Bihar election -- a comment by Mr Paras praising Bihar Chief Minister Nitish Kumar infuriated Chirag Paswan.
Chirag Paswan threatened to expel his uncle and reportedly declared: "You are not my blood."
Mr Paras was reported to have replied: "Your uncle is dead to you from now."
Uncle and nephew had hardly been on talking terms and even used to spar through letters.
Mr Paras, say sources, had never approved of his nephew's decision to contest the Bihar election separately from the BJP-led National Democratic Alliance (NDA), and field candidates against estranged ally Nitish Kumar. Those close to Mr Paras say he also felt sidelined when his nephew did not bother to check with him about the party's candidates.
In the November polls, the LJP's only achievement was to split votes in support of Nitish Kumar's Janata Dal United (JDU), which finished third and was reduced to junior partner in the NDA. The LJP won just one of 243 seats in the assembly.
In their growing frustration, exacerbated by the election debacle, LJP leaders saw Chirag Paswan as stubborn, arrogant and inaccessible. Sources said many of them saw Mr Paras as closer to Ram Vilas Paswan's style of functioning.
The LJP's crisis boiled over when Mr Paras, a first-time MP from Hajipur, was promised a spot in the central cabinet, reportedly by NDA leaders.
Nitish Kumar, sources say, had already been working on the rest of the LJP MPs through a party leader related to the Paswans - Maheshwar Hazari. His close lieutenant Lalan Singh kept up the outreach in Delhi.
The rebels, including Chirag Paswan's cousin Prince Raj - the son of another uncle -- Chandan Singh, Veena Devi and Mehboob Ali Kaiser, finally decided to follow Mr Paras.
For Chirag Paswan, another deep cut is the defection of his cousin Prince Raj, who had been appointed the LJP's Bihar president.
Prince Raj stays at the same house in Delhi as Mr Paras and this afternoon, he did not come out to meet his cousin either.