It is no secret that Karanja Kibicho and Nairobi's Governor Sonko do not like each other.
There is no love lost between them.
Not so many people knew about Mr Kibicho until Sonko fired a series of brutal salvos at him.
Local media outlets have been awash with reports on this long-running 'antagonism' that show no signs of coming to a close.
The flamboyant governor has charged numerous times that Kibicho is out to undermine him and was vehemently opposed to him becoming the governor of Nairobi.
But who is this bespectacled man Karanja Kibicho allegedly giving Sonko sleepless nights?
Well, Karanja Kibicho is Kenya's Interior Principal Secretary and served as the Principal Secretary in the Ministry of Foreign Affairs during Amina Mohamed's tenure.
He is a well-schooled technocrat who holds a Bachelor of Science and a doctorate in Mechanical Engineering.
Before joining public service, he served in various positions including being the production engineer of the Auto Springs Manufacturers.
As a testament to his intellectual brilliance, he has written wide-ranging engineering dissertations and taught in quite a number of universities in Kenya and overseas.
He is believed to be a member of Uhuru's tightly-knit circle, advising the president on various issues.
Recently, Governor Sonko accused him of conspiring to portray the Nairobi County administration as tribal.